Tag Archives: nature

Arctic permafrost: sleeping giant, or ticking time bomb?

Arctic permafrost melting – a 2004 photo

For those with some understanding of the climate system, and the danger of amplifying feed backs (or positive feed backs) the CO2 and methane currently buried under the Arctic permafrost is of concern. Now it seems it is leaking – out gassing – in greater quantities. Science Daily reports

Permafrost (perennially frozen) soils underlie much of the Arctic. Each summer, the top layers of these soils thaw. The thawed layer varies in depth from about 4 inches (10 centimeters) in the coldest tundra regions to several yards, or meters, in the southern boreal forests. This active soil layer at the surface provides the precarious foothold on which Arctic vegetation survives. The Arctic’s extremely cold, wet conditions prevent dead plants and animals from decomposing, so each year another layer gets added to the reservoirs of organic carbon sequestered just beneath the topsoil.

Over hundreds of millennia, Arctic permafrost soils have accumulated vast stores of organic carbon — an estimated 1,400 to 1,850 petagrams of it (a petagram is 2.2 trillion pounds, or 1 billion metric tons). That’s about half of all the estimated organic carbon stored in Earth’s soils. In comparison, about 350 petagrams of carbon have been emitted from all fossil-fuel combustion and human activities since 1850. Most of this carbon is located in thaw-vulnerable topsoils within 10 feet (3 meters) of the surface.

But, as scientists are learning, permafrost — and its stored carbon — may not be as permanent as its name implies. And that has them concerned.

“Permafrost soils are warming even faster than Arctic air temperatures — as much as 2.7 to 4.5 degrees Fahrenheit (1.5 to 2.5 degrees Celsius) in just the past 30 years,” Miller said. “As heat from Earth’s surface penetrates into permafrost, it threatens to mobilize these organic carbon reservoirs and release them into the atmosphere as carbon dioxide and methane, upsetting the Arctic’s carbon balance and greatly exacerbating global warming.”

Current climate models do not adequately account for the impact of climate change on permafrost and how its degradation may affect regional and global climate. Scientists want to know how much permafrost carbon may be vulnerable to release as Earth’s climate warms, and how fast it may be released.

Research is under way:

CARVing Out a Better Understanding of Arctic Carbon

Enter CARVE. Now in its third year, this NASA Earth Ventures program investigation is expanding our understanding of how the Arctic’s water and carbon cycles are linked to climate, as well as what effects fires and thawing permafrost are having on Arctic carbon emissions. CARVE is testing hypotheses that Arctic carbon reservoirs are vulnerable to climate warming, while delivering the first direct measurements and detailed regional maps of Arctic carbon dioxide and methane sources and demonstrating new remote sensing and modeling capabilities. About two dozen scientists from 12 institutions are participating.

“The Arctic is warming dramatically — two to three times faster than mid-latitude regions — yet we lack sustained observations and accurate climate models to know with confidence how the balance of carbon among living things will respond to climate change and related phenomena in the 21st century,” said Miller. “Changes in climate may trigger transformations that are simply not reversible within our lifetimes, potentially causing rapid changes in the Earth system that will require adaptations by people and ecosystems.”

Image source: Arctic Science Journeys

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The new normal: Europe hasn’t seen flooding this bad since the middle ages (you read that correct)

The River Danube flooding (Austria):

danube_floodwall

…welcome to the Anthropocene and the new normal.

Dr. Jeff Masters:

A historic multi-billion dollar flood disaster has killed at least eighteen people in Central Europe after record flooding unprecedented since the Middle Ages hit major rivers in Austria, the Czech Republic, Germany, Poland and Slovakia over the past two weeks. The Danube River in Passau, Germany hit the highest level since 1501, and the Saale River in Halle, Germany was the highest in its 400-year period of record.

Numerous cities recorded their highest flood waters in more than a century, although in some locations the great flood of 2002 was higher. The Danube is expected to crest in Hungary’s capital city of Budapest on June 10 at the highest flood level on record, 35 cm higher than the record set in 2006. The flooding was caused by torrential rains that fell on already wet soils.

In a 2-day period from May 30 – June 1, portions of Austria received the amount of rain that normally falls in two-and-half months: 150 to 200 mm (5.9 to 7.9″), with isolated regions experiencing 250 mm (9.8″). This two-day rain event had a greater than 1-in-100 year recurrence interval, according to the Austrian Meteorological Agency, ZAMG. 

Prior to the late May rains, Austria had its seventh wettest spring in 150 years, which had resulted in the ground in the region becoming saturated, leading to greater runoff when the rains began.

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Denying, not waving: image of the day and the fate of island nations

A wonderful cartoon from yesterday’s Sydney Morning Herald:

Source: Fairfax Media

Source: Fairfax Media

Even more important, an article highlighting the plight of small island nations:

The delegation of parliamentarians from four tropical Pacific Islands nations braved the Canberra cold last week, and that wasn’t the only climate shock they suffered. 

They watched the impressive intellectual exchange of question time in the House of Representatives on Wednesday and then moved on. But almost as soon as they left, Parliament started to debate a motion on whether the science of man-made climate change was real. This came as a bit of a jolt to the legislator visiting from Kiribati, a country of about 100,000 people on 33 small, low-lying islands strung along 5000 kilometres of the equator. 

“Climate change is real in our places,” Rimeta Beniamina, a government MP and vice-chairman of his parliament’s climate change committee, told me, expressing surprise at what was going on in the chamber a few metres away. 

“A few years ago it was not taken very seriously. But now quite a few villages are experiencing hardship. Beaches are eroding, houses are falling down, crops are damaged and livelihoods are destroyed. 

“The intrusion of salt water is very evident. The sea level may be rising millimetres a year, but it is still rising. The strong winds and rising tides are the worst part. Once the salt water enters the land, that’s it. Trees are falling along the coast, crops dying, pigs and chickens are affected.” 

A US study published at the weekend in the journal Nature Geoscience found the global sea level had risen by 16.8 millimetres between 2005 and 2011. 

Clark Wilson, a co-author of the study and geophysicist at the University of Texas at Austin, says: “There was an increase in the melting rate in Greenland starting in 2005 and that is probably the underlying story why,” according to the Wall Street Journal. The academic study was funded by NASA and the US National Science Foundation. 

The rising seas are whipped up by increasingly severe El Nino weather cycles, damaging the coastlines of countries including Kiribati, pronounced kee-ree-bas. 

“Some communities have been forced to move backward from the coast,” Beniamina says. “The problem is, there is not much land to move back to.” 

People are jamming into the overcrowded main island, Tarawa. Its centre has a population density estimated at three times that of Tokyo, says an April report by Australian journalist Bernard Lagan in the Global Mail. Fresh water supplies are at risk and there is not enough land to bury the dead. 

Kiribati President Anote Tong has declared a policy of orderly evacuation that he calls “migration with dignity”. The nation is a proverbial canary in the carbon emission coal mine, and the prognosis is unhappy.  

 

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Children, to have or to have not: be childless for the environment?

WtD's garden: winter vegetables on display for every passer by to see

WtD’s garden: winter vegetables on display for  all to see

The topic of children frequently comes up in the climate discussion.

Not merely about the kind of future the children of today – and future generations – will inherit, but should people be even having children at all?

Such thinking stems from the belief there are “too many people” on the planet; if we simply reduced our numbers it will mitigate our species environmental impact.

It’s a fraught debate to say the least.

However I wanted to write as a parent concerned about climate change, but also sympathetic to those who express this view.

Let me begin: the decision to have, or not have, a child is one of the most significant decisions an individual can make. I know, I’m the parent of a 5-year-old.

To have a child – or not – cannot be labelled a selfless or selfish act. We all have the right to control our life and bodies – regardless of gender, age, race, and sexual orientation. The question about having children is personal. No one should answer it for you.

But the question people sometimes ask is how much difference will it make to the environment if they remained childless? And is that the only course of action?

To answer this question, let’s start with some perspective.

All organisms – regardless of the species – leave an imprint and shape the Earth. Humanity does, so do ants and so do microbes. All life shapes the biosphere – life is an integral component of the climate system itself. Consider the role of plants in regulating the climate. But also consider the impact humanity is having: changing the atmosphere and ushering one of the six major mass extinction events of the last 560 million years.

Those who understand the deep history of the Earth and the climate know how radically different the planet has been over the vast eons. Remove humanity from the planet, and the climate will continue to change.

What matters to us – today – is the type of change we are inducing. How fast, how disruptive and how much potential suffering will these changes induce?

Thus to my mind, the question about having children is framed incorrectly.

Let me rephrase it thus: is having any impact negative?

My response: no, not at all.

Even if we substantially reduce the individual carbon footprint of every person on the planet, we will continue to have an impact at the local, regional and global level.

What matters is the scale of the impact an individual or community has. It is not the numbers of individuals that matter, it their level of consumption and resource use. 

If you move through world disregarding the impact you have, thoughtless about the harm you are inflicting it does not matter if you have a child or not.

A childless CEO flying from point to point in their Learjet, driving a SUV and investing in the fossil fuel industry will do more harm than 1000 families living modestly and within environmental constraints.

Help life find the places to grow

Car park converted into productive space for growing food

Car park converted into productive space for growing food

Let me tell you a story.

A few weekends back my five-year old daughter and I were tending our vegetable patch.

We started growing it with neighbors in the front yard of our apartment, right on the street. Anyone who walks past can see the vegetable patch (see the photo above). I’ve seen people grab a sprig of rocket – and that’s OK.

As we tended our garden people stopped to talk. Others smiled as they walked past. My daughter helped, but really she spent a couple of hours playing in the mud. I planted an olive tree. I’m hoping it will fruit in a few years so I can start preserving my own home grown olives.

Out the back of the apartment complex you’ll find the spaces for the residents cars – a grey, flat and dull expanse of concrete. But in places the concrete is cracked, exposing the soil beneath.

A neighbor planted a cherry tomato plant in one of those cracks – it flourished, yielding the most delicious fruit. All during summer my daughter and I ate cherry tomatoes fresh of the vine. Food from a place were the only plants normally to be found are invasive weeds.

And why shouldn’t we plant food in that space?

It is merely a matter of perspective and convention that tells us certain spaces are for certain things.

Life can grow anywhere: sometimes it is our role to help life find those cracks in the pavement. In doing so we make something wonderful.

Through this simple activity of helping the garden grow I’ve come to know my neighbors; my daughter learns something about where food comes from; we all share fresh food.

This is what it means to be human: we are social creatures. We flourish when we belong to a community.

As a parent you experience both joy and hardship: but overall, children bring delight. Children bring joy. This is part of being human.

And yet I would stress (just as strongly) one can also live a joyous and flourishing life without being a parent. I know many such people, and regard their choices as valid. The lives they live are just as flourishing. At times, especially when parenting is hard, I envy their freedom from the responsibility of child rearing.

But that makes me human.

You can tread lightly: even as a parent

I live in the inner city: I use public transport, I sometimes walk to work and have a hybrid car. I cycle to social engagements. I’m active in the climate discussion.

I’ve changed my life in accordance to my values: but I’ve not made myself poorer in any way.

I work for a large company, but I restrict flying for meetings: I video-conference. I enjoy my role in a large professional services firm and receive a decent salary; I do not reject the free market outright, though I believe it needs to be appropriately regulated.

Ditching a large mortgage and most of the trappings of consumption was liberating. I don’t have a TV.

I’ve not sacrificed – I’ve gained.

I save more, have less stress and more time by having a smaller place.

In doing so I’ve rediscovered the insights philosophers over the centuries have extolled – live modestly; reflect on your actions; act ethically; the rest will follow.

What matters is the life you wish to lead – what will make that a flourishing life?

Only the individual can answer that. Picture that life, work towards it.

You can tread lightly – that can be done as a parent, or by making the valid choice not to be.

Remember, to have a child is not to commit oneself or your child to a life of mindless consumption.

You have a choice – you can teach your child to have the skills to make valid choices.

What better legacy is there but teaching your child about the universe, their responsibilities to others and the environment?

When they grow up, they may go into the world and teach others.

The legacy we leave does not have to be one of abstinence, or sacrifice only.

What matters is what you choose to value.

There are many paths and options open to you: don’t let anyone tell you otherwise.

The rest will follow.

—————–

[Note: I will watch the comments on this post carefully, NO debates about how climate change is a conspiracy between Greens and those advocating a radical eugenics program to de-populate the Earth. If comments becomes too “heated” offending posters will be banned.]

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Stopped clocks, bad debts and climate sceptics: or why the latest paper on climate sensitivity does not vindicate the sceptics (nor suggests complacency)

clock_broke

For those who pay attention to minutiae of the climate debate, you may have noticed the denial-blog-sphere is all-a-flutter with claims of “Sceptics proven right.”

This source of this self-congratulation among the sceptics is a recently published paper in Nature Geoscience titled Energy budget constraints on climate response by Alexander Otto et al [doi:10.1038/ngeo1836].

I was able to source a copy of the paper and took the time to appraise how it could possibly be the source of so much sceptic excitement.

Let me quote from the paper so that you may judge whether-or-not the sceptics have been vindicated:  

“The rate of global mean warming has been lower over the past decade than previously. It has been argued that this observation might require a downwards revision of estimates of equilibrium climate sensitivity, that is, the long-term (equilibrium) temperature response to a doubling of atmospheric CO2 concentrations…”

The paper notes:

“The most likely value of equilibrium climate sensitivity based on the energy budget of the most recent decade is 2.0 °C, with a 5–95% confidence interval of 1.2–3.9 °C…”

From this, sceptics have claimed the death knell of climate science. Having read it, the take home points are for me are:

  • the oceans have been sequestering a great deal of heat – much more and much more rapidly than we thought 
  • that will come to an end at some point in the future, with the heat coming back out as the climate system tries to reach a point of equilibrium (note: as the atmosphere and oceans exchange heat)
  • the rate of warming for the last decade has been at the lower end of model projections
  • thus in the short-term the climate may warm 20% more slowly than previously expected (i.e. transient climate response)
  • even though we may not see some of the extremes predicted in earlier models, a doubling of atmospheric CO2 concentration opens the door for an average temperature increase of +/- 4.0C.

Good news story and the death knell of the climate conspiracy?

Hardly.

The research is not that a radical departure from the results of climate science, but consistent with other work within the field.

It is also worth noting the paper does not take into consideration tipping points or other anticipated positive feedback mechanisms such as increased methane emissions – the release of vast quantities of this most potent greenhouse gas from beneath the Arctic tundra due to warming.

A small and maybe irrelevant point? Must likely not.

Indeed there are a quite few nasty surprises like methane out-gassing lurking out there – things known but generally avoided in many models (the planets decreasing albedo effect as the extent of the Arctic ice decreases anyone – anyone?).

It will be worth watching the research on climate sensitivity over the coming years: at least form the perspective of how policy makers, sceptics and the public react to this informaiton.

Just how fast, and how extreme, will the warming be?

A very interesting question indeed.  

Bad “climate” debts accumulating: no time for complacency

A 2.0C-4.0C increase in average temperatures will have a significant impact on large parts of the globe, if not devastating large swathes of it.

As the oceans draw down heat it will fuel their thermal expansion, a major driver of projected sea level rise. Nor will the oceans continue to do humanity a favour by acting as endless sink for the additional heat we’re adding to the climate system.

Crop production around the mid-latitudes is going to be hit hard, which incidentally is where most of humanity resides. Remember the aforementioned sea level rise? Many millions in the mid-latitudes will be forced to relocate.

But hey, wheat production will increasingly shift to Canada and the Arctic circle. You win some, lose some right?

Like avoiding a bad debt by taking out another high interest credit card to cover your repayments, this warming is going to raise its ugly head in the future. One may avoid paying your debts in the short-term, but at some point the Sheriff will come a-knocking and take the keys to your car and what personal property you have.

Likewise, the climate will come and “ask” us for the debt we “owe it”.

Things like coastal cities and productive farmlands will be the collateral confiscated to service the “warming debt” our species is accumulating.

Perhaps we’ve gained a little extra time – a tiny window of opportunity really – to bring down greenhouse gas emissions. Perhaps we have more time to plan adaptation measures.

Whatever the case, the window for action is still narrow: this research is not cause for complacency.

Sadly I fear laggard policy makers and the mischievous will see it as such, and continue to push the cause of inaction.

Deep time, deep history, climate change and living through interesting times

Let’s also place this “pause in warming” in context.

In geologic terms, the rapid increase in atmospheric CO2 and the warming trend is unprecedented in the planet’s history.

It is vital we stop thinking in terms of a climate change as the up-or-down temperature swings of a particular decade. We accuse sceptics of cherry picking; likewise we need to remove our own myopic filters.

We need to pay far closer attention to the paleoclimate record: as James Hansen has recently argued, we cannot fully appreciate the profound changes the planet is undergoing without drawing on the lessons of the geologic past.

Nor should we disregard the warming oceans, the decline of Arctic sea ice and the increasing levels of CO2 in the atmosphere – and the many other metrics – all point to the same conclusion: warming has not stopped.

Perhaps it is the own cognitive limitations and the transient nature of how we experience time that creates such a short-sighted and myopic view of climate change.

I suggest we think in terms of both deep time and deep history.

2.5 billion years from now, should our descendants or a successor species of comparable intelligence dig into the Earth’s crust they’ll find evidence of our civilisation: but not in artifacts or fossils.

Instead they will note the abrupt disappearance of species in the fossil record (evidence of a mass extinction event) and the changed chemical composition of ocean floor and terrestrial sediments.

The evidence will point to a warmer world relative to other periods within geologic history. Billions of years into the future, a faint but still distinguishable trace of humanity’s impact will be evident. 

That’s how profound and long-lasting the changes humanity has wrought are.

We’ve not seen this level of CO2 in the atmosphere in millions of years: most recently during the mid-Pliocene (5.3-2.5 million years ago).

At that point the average temperature was 3.0C-4.0C higher, while sea levels were 25 meters higher.

However, we won’t have the luxury of billions of years of perspective to ponder what happened: we’ll be living through those profound planet-shaping and epoch-defining changes.

Actually, we are living through those planet-shaping and epoch-defining changes.

Of stopped clocks and claims the planet is no longer warming

What also interests me is the sceptic response.

As anticipated, they’ve misinterpreted the paper and claimed it as vindication of their views.

My response to that is even a stopped clock gives the right time twice a day.

It’s well understood the rate of temperature change has varied over the last 150 years: to claim such a pause is evidence against warming is to merely be right by chance, and not for the reasons the sceptics likes to claim.

The sceptics are in no way vindicated: a slower rise in land temperatures does not imply climate change has stopped, or was “exaggerated”.

Indeed, lead author of the paper Alexander Otto makes that point in an interview with The Guardian:

“Otto said that this most recent pattern could not be taken as evidence that climate change has stopped. “Given the noise in the climate and temperature system, you would need to see a much longer period of any pause in order to draw the conclusion that global warming was not occurring,” he said. Such a period could be as long as 40 years of the climate record, he said…”

Sage advice the sceptics are won’t to ignore.

Which of course they do…

Perth’s resident climate sceptic and conspiracy theorist Jo Nova is the most self-congratulatory, breathlessly announcing they (sceptics) where right all along:

I think the climate sensitivity figure is still too high but it’s good to see estimates being revised in the right direction. Reality bites back. The deniers were ahead of the climate experts. We said the models were exaggerating and we were right.

Andrew Bolt in his usual fashion is not even close to being wrong claiming “alarmists” have finally admitted defeat:

Sure, warmists exaggerated the temperature rise so far, The Age finally admits. But we still have to believe they’ll be right about the apocalypse to come:

The rate of global warming caused by rising greenhouse gas levels could be slower than previously thought, but will still result in the same eventual higher temperatures as earlier forecast, new research has found.

Note also the story suggests there has been a “rate of global warming” over the past decade, without actually telling you what it is. If the reporter did, he’d have to admit there’s been no warming at all…

Bolt completely misrepresents the results of this paper; his view that there has been no warming is completely contradicted by Otto’s statements – whose work Bolt seeks to misappropriate to support his fallacious argument.

Bolt also gets it spectacularly wrong in his first sentence: no one is revising historical temperature increases down (as his wording implies), they are revising the short-term (i.e. transient) rise in the global temperature average slightly down over the coming decades.

Global warming has not stopped; it just may have hit a very small and minor speed bump. It is virtually certain to pick up speed again. 

Thus it would seem Mr. Bolt is struggling with such basic concepts as the past and future. But, hey like whatever Andrew: us warmists have always got it wrong.

I’m sure he got his “facts” from Watts up with That? or some other climate sceptic blog and they fitted nicely with his prejudices – he tags the post “Dud predictions” without fully appreciating what he is posting.  

Sorry to disappoint Andrew, but we’re still heading towards a much warmer world.

The sceptic response: the enemy of my enemy is the fact we can cherry pick

What’s remarkable here is not the paper itself, but the sceptic response. Indeed, their response is ripe with irony.

For decades sceptics have claimed the models constructed by climate scientists are unreliable and not to be trusted.

And yet, when a model or a piece of research shares the barest hint of concordance with their views they proclaim it as a victory for sceptics.

It seems the old adage “the enemy of my enemy is my friend” applies. 

To paraphrase in sceptic terms, “the enemy of my enemy is the facts I can cherry pick”.

Sceptic victory?

Hardly.

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2013 Arctic ice maximum: 10 straight years of declining sea ice peak

NASA providing the video: the above is an interesting fact. The maximum extent of the Arctic sea ice was the “sixth smallest” recorded in 35 years of satellite observation.

As you watch the video you can see some amazing images:

  • An August 2012 cyclone helped break up the sea ice, sending a large pack into warmer southern waters
  • Ice north of Alaska was subject to fracturing, with cracks in the ice “hundreds of miles long” – most likely due to thinner sea ice

Each year, the sea ice maximum gets smaller, this year it reached its maximum of 15.13 square kilometers on March 15. As the National Snow and Ice Data Centre notes, the ten lowest maximums have occurred in the last ten years:

Arctic sea ice reached its maximum extent for the year on March 15 at 15.13 million square kilometers (5.84 million square miles). This year’s maximum ice extent was the sixth lowest in the satellite record (the lowest maximum extent occurred in 2011). The ten lowest maximums in the satellite record have occurred in the last ten years (2004 to 2013).

Such data puts to rest the “temperatures have plateaued” nonsense. You can see the 2013 maximum against the 1979-2000 median:

Such data puts to rest the “temperatures have plateaued” nonsense.

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More angry, more often: March heatwave signals a new normal

From The Conversation, more on Australia’s record breaking “Angry” summer: enjoy! 

By Sophie Lewis, University of Melbourne and Sarah Perkins

Daylight hours are dwindling and our first month of autumn is ending. But in many places, March felt a lot like summer. Get used to it: looking ahead, all indications are that future summers could be just like this one, or more extreme.

Southeast Australia welcomed autumn with a persistent heat wave. For the first 12 days of autumn, temperatures were 6.9 degrees above normal across Tasmania and 6.8 degrees above normal in Victoria.

Melbourne’s March record-breaking weather included nine days of temperatures of 32 degrees or above and its hottest overnight March temperature in 110 years of record keeping. Adelaide experienced ten such hot days.

The unusually warm autumn weather was part of a much larger and much longer warm spell. The last six months have been characterised by sequences of heat waves and record temperatures across the entire Australian region.

Summer was the hottest on record across all of Australia. In January, Australia had its hottest month on record. The hottest day ever recorded for the entire continent occurred on January 7.

The surrounding oceans, from the Great Australian Bight through Bass Strait, also broke previous extreme temperature records. These waters exhibited the hottest sea surface temperatures on record in February.

Our exceptionally hot summer cannot be discussed simply as a catalogue of interesting record-breaking events. This summer was not normal. And we can’t talk about the exceptionally hot summer and early autumn without talking about climate change.

Australian average temperatures have increased faster than the global average increase (0.8°C) and are now 0.9 degrees warmer than a century ago.

It may not sound like much, but research shows that changes in average temperatures (even less than 1°C) can lead to huge changes in the frequency and severity of extreme climate events.

This is exactly what Australia just experienced with this sequence of heat waves, extending from November 2012 to March 2013.

Our recent research in the internationally peer-reviewed Journal of Climate shows that there has been a significant increase in the number of heat wave days for most of the country from 1951-2008. The paper describes heat waves as a period of three or more days where temperatures are excessively hot – in the top five to 10% of temperatures recorded.

This trend is greatest in eastern Australia, where both the number of heat waves and their duration has increased.

Recently, we extended the time period of the analyses to include the period from 1911 to 2011. Not surprisingly, our initial results suggest that heat waves are now occurring earlier than 100 years ago. In some places, the first heat wave of the season is occurring almost a month earlier.

Recent studies from other parts of the world have shown that many, if not most, of the recent record-breaking heat waves and extremely warm summers would have been unlikely to occur without human influence on climate change.

Although we can never say categorically whether an individual climate event, such as a heat wave, would have occurred without human-related greenhouse gas emissions, it is possible to assess how global warming has changed the likelihood of extreme events occurring.

Working with other climate scientists we investigated the probability of extreme summer heat occurring across Australia using a suite of climate model simulations representing current climate conditions. We then used a parallel suite of control experiments, in which greenhouse gases from human activities were entirely absent.

Previous studies using similar methods have found strong human contributions to the severity of extreme summer temperatures. James Hansen and other NASA scientists found a 10-fold increase in areas experiencing extremely hot summers due to global warming. Similarly, climate scientist Gareth Jones and his colleagues at the UK Met Office Hadley Centre found a dominant human influence on rapidly increasing hot summers in the Northern Hemisphere.

When we ran our hot, angry summer through a large group of the latest generation of climate models it became clear that there was likely to have been a substantial human influence on our recent extreme summer heat. Our early results indicate that anthropogenic climate change more than tripled the risk of Australia’s extremely hot summer occurring.

As for the future, it is now virtually certain that the frequency and severity of hot days will increase. Extremely hot seasons will worsen, with the biggest impacts of climate change being felt by Australians in summer. Spring weather will come earlier, and autumn later.

Additional global warming over the next 50 years, under a business-as-usual fossil fuel emissions scenario, is expected to see global average temperatures increase by at least 1°C. Such a change means that our recent summer on steroids will become the norm and far worse summers will occur with greater frequency.

We already know what is causing the changes we see now. Clearly, it is time to stop talking about record-breaking heat as isolated incidents and recognise them in the context of climate change.

It’s time to start preparing for more angry summers, more frequently.

Sophie Lewis receives funding from the Australian Research Council.

Sarah Perkins is a research associate at the UNSW node of the ARC Centre of Excellence for Climate System Science.

The Conversation

This article was originally published at The Conversation.
Read the original article.

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Melbourne’s exceptional heatwave and climate change: this ain’t the weather your grandparents knew

St.Kilda Beach in the 1930s: when life was simpler, and the planet cooler

St.Kilda Beach in the 1930s: when life was simpler, and the planet cooler*

Melbourne is famous for its extremes of weather. As the old Crowded House song so beautifully put it, to live in Melbourne is to experience Four Seasons in One Day

We’re accustomed to blistering summers and bone-chilling winters. Less familiar are blistering Autumns.

For those who didn’t know, Melbourne is in the midst of a record-breaking heat-wave that has seen the temperature stay above 30 degrees Celsius for eight days now.

Nor is there any relief in sight; according to the Bureau of Meteorology we can expect at least two more days and nights of extreme heat.

This will surpass the previous record of seven days set in February 1961.

The remarkable fact is that we’re officially in Autumn.

According to the Country Fire Authority (CFA), by Wednesday the entire state will be exposed to some risk of bush or grass fires. Areas marked blue denote areas of high fire danger, those coded yellow pertain to areas of very high fire danger:

CFA update

CFA update for Wednesday 13/3/2013

Without doubt we’re entering a new climate regime:

Future warming of the climate due to greenhouse gas emissions will very likely lead to further increases in the frequency of unusually hot days and nights and continued declines in unusually cold days and nights.

These changes will result in weather events which are increasingly beyond our prior experiences.

The climate denial crowd will try to tell you “It’s just weather!”

Or they’ll claim it was just as hot fifty, seventy or one hundred years ago. 

There may have been some hot days – but this heatwave ain’t nothing our grandparents, or our great-grand parents ever experienced.

The world has warmed during the last 150 years: the present heat wave is a harbinger of future extremes.

Welcome to the Anthropocene.

 

*Source: Museum of Victoria

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Stunner: The hockey stick just got scarier, a new temp reconstruction of the last 11k years

Published today in Science, the paper A Reconstruction of Regional and Global Temperature for the Past 11,300 Years (Marcott et.al) shows the stunning – hell, terrifying – increase in temperatures that has taken place since industrialisation.

Michael Mann’s famous hockey stick graph reconstructed the temperature for the last 2000 years. It not only became iconic, but a target for those wishing to cast doubt on the science.

Marcott et.al. do not merely replicate Mann’s work, but extend the time-frame to cover the previous 11,000 years:

Surface temperature reconstructions of the past 1500 years suggest that recent warming is unprecedented in that time. Here we provide a broader perspective by reconstructing regional and global temperature anomalies for the past 11,300 years from 73 globally distributed records. Early Holocene (10,000 to 5000 years ago) warmth is followed by ~0.7°C cooling through the middle to late Holocene (<5000 years ago), culminating in the coolest temperatures of the Holocene during the Little Ice Age, about 200 years ago. This cooling is largely associated with ~2°C change in the North Atlantic. Current global temperatures of the past decade have not yet exceeded peak interglacial values but are warmer than during ~75% of the Holocene temperature history. Intergovernmental Panel on Climate Change model projections for 2100 exceed the full distribution of Holocene temperature under all plausible greenhouse gas emission scenarios.

To put into perspective, before the founding of the first cities.

Our civilisation has existed in “the sweetest of sweet spots” – a time of relatively stable climatic conditions.

In the last 10,000 years we have seen the emergence of agriculture, the establishment of great cities, the founding of great civilisations and the invention of writing.

None of this would have been possible without a benign and forgiving climate.

What is different about the past century and a half is the speed of those changes: note the spike in temperature anomalies for what is essentially the period of industrialisation (1850 ff). 

The climate has always changed: no self-respecting scientist or climatologist has ever denied this. Temperature records are but one proxy of this change – the multiple lines of evidence for climate change are overwhelming.

Note also the last sentence in that abstract: Intergovernmental Panel on Climate Change model projections for 2100 exceed the full distribution of Holocene temperature under all plausible greenhouse gas emission scenarios.

To translate: all the models point to a future that is warmer than anything we’ve seen for the last 10,000 years.

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Hot planet – great free BBC documentary on what a 3 degree world may look like

Dear all, still busy at work. In the interim I highly recommend this great documentary as Video of the day:

It showcases: 

  • how scientists measure the historical concentration of CO2 using Antarctic ice cores
  • the changes to ecosystems such as coral reefs, Canadian forests and the Africa savanna
  • a complete loss of Arctic sea ice by 2040
  • the dramatic increase in the duration of the US wildfire season
  • what we can expect in a 3 degree world

Enjoy!

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