From Bad to Worse: Climate Change and Greenhouse Gas Emissions
In the debate around climate change, the future effects of man made carbon emissions are all too often over looked. The recent publication by the Intergovernmental Panel on Climate Change (IPCC) of the Special Report on Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation (SREX) presents a concise summary of what we face, and it doesn’t look good.
The report consolidates much of what is known about the trends in climate that have occurred over the last 60 years. It notes that it is very likely (90-94% probability) that the world has seen a decrease in the number of cold days and nights, with a corresponding increase in hot days and nights. It is likely (66-89% probability) that regions have recieved increased precipitation. It is also likely that the increase in extreme coastal water levels are linked to increased sea levels. The report notes that there is low to medium confidence in linking climate change to increased cyclone, drought and flood incidence and intensity, though this is due to a historical lack of data.
However the most concerning part of the report is what it predicts for the future. It notes that it is virtually certain (95-100% probability) that temperatures will increase. It is very likely that sea levels will continue to rise, fueling extreme coastal high water levels. It is likely that the world will see heavier precipitation and higher cyclone winds. The report also predicts increases in drought intensity, heat waves and glacial melts.
Though even worst then this, it’s possible the SREX underestimates the future impacts of climate change. Indeed, international reports such as SREX have long been criticised for being too conservative. Specifically though in this case, the report predicts that under the A1B and A2 scenarios (the highest greenhouse emissions projections provided in the IPCC’s Fourth Assessment Report from 2007), 1-in-20 year hottest days are likely to become 1-in-2 year events. Similarily, 1-in-20 year precipitation records may be reduced to 1-in-5 year events. The problem with this of course is that at the moment, both the A1B and A2 scenarios are lagging real world emissions growth. A 2010 review by the Australian Academy of Sciences showed observed greenhouse gas emissions higher than any of the scenarios previously predicted by the IPCC.
It also seems this trend is continuing unabated. It was hoped that the global financial crisis could stem the emission rises, perhaps even causing cuts of up to 3%. Instead emissions rose to record levels.
This has been confirmed this week by the release of the World Meterological Organisation’s Greenhouse Gas Bulletin. The report shows recent increases in carbon dioxide, methane and nitrous oxide emissions and atmospheric concentrations to record levels.
For carbon dioxide, not only is the atmospheric concentration at a record level, but the emissions growth rate is higher than the average increases recorded over the 1990’s or the 2000’s. However, even more frightening than this is the increase in methane emissions, which the report puts down to “biogenic” sources. That is, methane emissions from such things as melting permafrost. Not only is methane a much more potent greenhouse gas than carbon dioxide, the emissions represent a potential tipping point, the much feared scenario where anthropogenic warming triggers natural feedback mechanisms. This in turn causes further warming, causing the climate to enter a cycle in which mitigation is becomes very difficult to impossible.
This initial triggering of tipping points should be of grave concerns. Not only are our own emissions spiraling out of control, but we may be causing warming of which we have little control of. These factors combined suggest that many of our current assumptions may be far too conservative, and that the threats we face are graver than we previously thought.
Yet, as I have discussed before, the actions taken by our Governments are far too inadequate to deal with climate change. The International Energy Agency estimates that by 2017, enough polluting infrastructure will be built to lock in emission increases that will eventually drive the world into a climate crisis. Yet despite this there is news out today that shows developed countries are aiming to delay any international agreement on climate change until 2016.
The science, of course, is now in. It has been for decades now. The question now becomes whether or not the politics will follow.
Image from: http://scienceandmedia.wordpress.com/2011/08/25/raising-mass-awareness-through-a-lack-of-scientific-accuracy/
