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Critical Decade for Climate Action – New Report Echoes Many Others: We Must Decarbonize to Stabilize Climate

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We’re living in a crucial time for action on climate change. Two years on from a report on the “Critical Decade,” the Australian Climate Commission published an update today. According to the update, the years from 2011 to 2020 are the time during which we must begin to turn around our heat-trapping emissions in order to stabilize the climate system and limit increasingly dangerous impacts.

The new report is an important precursor to both the Intergovernmental Panel on Climate Change’s (IPCC) Fifth Assessment Report, the first part of which is due out in late September of this year; and the Third U.S. National Climate Assessment, which is undergoing its review (see the draft here) before being released in 2014.

All of these publications underscore the urgency of the latest climate science and the need to act quickly in addressing one of the most pressing issues of our time — human-caused global warming.

Here are three important highlights from the new report:

1. Most of the available fossil fuels simply cannot be burned

If we are to stabilize climate this century, most of the available fossil fuels cannot be burned. Estimates in this report show we can emit at most 1,000 billion tonnes of carbon dioxide from the year 2000 until mid-century to give us the best chance of limiting global temperature rise to 2oC (3.6o F) above pre-industrial temperature. The nations of the world have agreed that the consequences of a 2oC rise in global temperature are so severe for the health and well-being of humanity and systems it depends on that it is a threshold that should not be crossed. Although, this story is evolving as new science is pointing to dangerous impacts under less warming — leading some to call for a 1.5o C limit.

However, in the first 13 years of this critical period, the world has emitted nearly 40 percent of that budget already. The rate we are emitting carbon dioxide is also accelerating, with a 2.6 percent increase just between 2011 and 2012. (See more at the Global Carbon Project here.) Stabilizing the climate within the 2oC temperature limit remains possible, but unless we intensify our efforts this decade and beyond, the promise international leaders made in 2009 will be forever broken.

Overspend in the Carbon Budget (Source: The Critical Decade 2013)

2. The risks scientists warned us about are already happening

There is consensus that many of the climatic changes we are currently seeing are due to human activity. Some of the consequences already evident are rising seas and changing rainfall patterns.

One dramatic change is the heating of the ocean globally. Over the period 1961 to 2003, almost 90 percent of the extra heat from human-caused global warming has been absorbed by the ocean. This dramatic rise in water temperature is not only raising sea level by thermal expansion but is also affecting the chemistry and biology of the world’s oceans and affecting the hydrological cycle, impacting areas far removed from the oceans themselves. (See more at NOAA Oceans and the U.S. National Oceanographic Data Center.)

The influence of climate change on the water cycle – higher surface water temperatures and air temperatures speed up the hydrological cycle (Source: The Critical Decade 2013)

3. Scientists know more about abrupt and irreversible changes

Scientists are improving our understanding of abrupt and irreversible changes in the climate system, known as tipping points. The most concerning of these are the melting of the world’s great ice sheets, shifts in the Indian summer monsoon, and changes to the patterns of rainfall in the Amazon basin. Many of these processes can have direct impacts on human well-being on a large scale.

The conclusion of the report is clear and repeats what was stressed in the initial report two years ago – this is the decade to begin decisively decarbonizing the economy. Time is of the essence.

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About the author: Melanie Fitzpatrick, a climate scientist with the UCS Climate and Energy Program, is an expert on local and global impacts of climate change. She holds a Ph.D. in Geophysics from the University of Washington, specializing in the role of sea ice and clouds in Antarctica. See Melanie's full bio.

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