Tag Archives: greenhouse gas emissions

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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Gang of four: can developed and developing countries act in concert to avoid a world of 2ºC plus?

A recent article in Nature: climate change highlights the growing consensus that if action isn’t urgently taken to reduce greenhouse gas emissions (GHGs) humanity we will fail to keep global average temperatures below 2ºC:

On going climate negotiations have recognized a “significant gap” between the current trajectory of global greenhouse-gas emissions and the “likely chance of holding the increase in global average temperature below 2 °C or 1.5 °C above pre-industrial levels”.

The article by Glen Peters, Robbie Andrews et.al titled The challenge to keep global warming below 2ºC examined looks at historical GHG emission levels and compares those to the emissions scenarios used in all previous four IPCC reports:

Long-term emissions scenarios are designed to represent a range of plausible emission trajectories as input for climate change research. The IPCC process has resulted in four generations of emissions scenarios: Scientific Assessment 1990 (SA90), IPCC Scenarios 1992 (IS92), Special Report on Emissions Scenarios (SRES), and the evolving Representative Concentration Pathways (RCPs) to be used in the upcoming IPCC Fifth Assessment Report.

One merely needs to look at the following graph to see how we are tracking:

 Nautre

Note the black line – historical emissions – and contrast that to the mass of other lines, the alternative emission pathways. For the uninitiated or confused it shows GHG emissions inline with the various “business as usual” (BAU) scenarios developed in the previous four IPCC reports. Each year we are pumping increased levels of CO2 and other GHGs into the atmosphere.

Just in case it isn’t clear this alternative graph from the same paper shows the annual percentage increase in CO2 emissions and how they track against the various scenarios:

 Tracking_pathways

Emissions have been growing at least 2% per annum without pause – exactly what you’d expect to see under BAU scenarios. In the IPCCs Fourth Assessment report these were referred to as the A1 scenarios:

The A1 storyline and scenario family describes a future world of very rapid economic growth, global population that peaks in mid-century and declines thereafter, and the rapid introduction of new and more efficient technologies.

Within the A1 group of scenarios there are several scary emission pathways you want to avoid if you don’t want to push average global temperatures 2ºC and beyond. In the upcoming fifth assessment report the high emissions path will be referred to as RCP8.5 (there are four RCPs or Representative Concentration Pathways).

Short version?

We’re well on track for a world of 2ºC if we don’t act within the next few years. The authors note we can avoid such a situation but only if we act with a sense of urgency by 2020:

Current emissions are tracking slightly above RCP8.5, and given the growing gap between the other RCPs (Fig. 1), significant emission reductions are needed by 2020 to keep 2 °C as a feasible goal. To follow an emission trend that can keep the temperature increase below 2 °C (RCP3-PD) requires sustained global CO2 mitigation rates of around 3% per year, if global emissions peak before 2020…

To translate “sustained global CO2 mitigation rates” means rapidly decarbonising our economies over a period of many years – decades even. Emission rates need to fall dramatically and sooner rather than later.

It’s worth thinking about this in context of the most recent round of negotiations at Doha (COP18), which like nearly all of its predecessors has delivered underwhelming results.

The Gang of Four and beggar they neighbour: who needs to lead?

The authors note the close cooperation and coordination of four countries (or three countries and one region) will be key to mitigating GHG emissions:

To move below the RCP8.5 scenario — avoiding the worst climate impacts — requires early action and sustained mitigation from the largest emitters such as China, the United States, the European Union and India.

These four regions together account for over half of global CO2 emissions, and have strong and centralized governing bodies capable of co-ordinating such actions. If similar energy transitions are repeated over many decades in a broader range of developed and emerging economies, the current emission trend could be pulled down to make RCP3-PD, RCP4.5 and RCP6 all feasible futures.

They make a key point: the “Gang of Four” account for over 50% of all global GHG emissions and all of them have the capacity to lead the world in implementing solutions to bring down emissions to safe levels.

The developing nations – lead by China and India – have been exhorting the developed nations to make deep cuts to emissions, assist in technology transfer and provide funding for mitigation and adaptation initiatives. Nor should we forget the fact that both China and India have seen profound economic growth over the past several decades: they’re not keen to sacrifice this unless the United States and other developed nations act in concert with them.

The developed nations – the United States chief among them – have been unwilling to undertake the deep cuts or pledges for technology transfer and funding out of self interest. Nor do they wish to surrender their present economic and political advantages to developing nations such as China.

Each of the Gang of Four fears it will be a case of beggar thy neighbour: in making sacrifices they will be taken advantage of.

But really it is a case of the tragedy of the commons: acting unilaterally and out of self interest each party not only beggars the other, but also their own future.  

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Rapid warming unavoidable?: Hansen et.al presents on the state we’re in (must watch video)

The American Geophysical Union is currently holding a conference in San Francisco. Over 20,000 people are attending the conference. Fortunately for us, many of the presentations are being posted to YouTube and there is an amazing volume of science available on the site freely available.

James Hansen and others recently presented on the potentional for rapid warming in this 2011 video. It is an important video, and well worth watching:

In a nutshell: we can’t afford to keep burning fossil fuels and releasing them into the atmosphere.

Stephen Lewandowsky gives a good overview:

Science is debate, and the AGU meeting is the biggest annual debate of climate scientists in the world. It is a debate that extends over five days, each filled with 12 hours or more of non-stop science. 

There is, however, one issue that is not being debated: Nowhere is there a debate about the fundamental facts that the globe is rapidly warming and that human greenhouse gas emissions are responsible for that warming. 

That scientific debate ceased decades ago. 

It is only in the fantasy world of climate denial that ignorant chatter about those physical fundamentals continues, to the detriment of the public which would be better served without such distracting noise. 

Among the 20,000 geophysicists and scientists from other disciplines in attendance at the AGU meeting, there is no mention of the denialist troupe of cranks who do “science” by writing letters to the editor. 

With one exception. 

Dr. Jim Hansen, one of the world’s foremost climate scientists, who first alerted the world to the risks from climate change decades ago, gave a presentation on Tuesday night. A patrician figure, he was greeted with a standing ovation even though the message he had to deliver, based on the latest available science, was far from encouraging. Decades ago, Dr. Hansen predicted events such as Hurricane Sandy, and he has been warning about the implications of climate change ever since. 

Dr. Hansen expressed the view that the professional dis-informers who facilitate and encourage climate denial, and who obstruct and delay a solution to the problem at great cost in dollars and human lives in support of their own short-term greed or ideological agenda, ought to be tried for crimes against humanity.

Watch the video to see how science is really done.

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