Tuesday, December 15, 2009

The Copenhagen Diagnosis

The University of New South Wales Climate Change Research Center has put together a report surveying scientific papers that have been published since the 2007 Intergovernmental Panel on Climate Change (IPCC) completed its fourth Assessment Report over three years ago.

“The Copenhagen Diagnosis: Updating the World on Latest Climate Science” found that many climate indicators are worsening at a faster pace than predicted by the IPCC.

Global carbon dioxide emissions from fossil fuels in 2008 were 40% higher than those in 1990 with a three fold acceleration over the past 18 years. This tracks near the highest scenarios considered by the IPCC. At the same time the fraction of CO2 emissions absorbed by the land and ocean appears to have decreased from 60% to 55%.

A wide variety of satellite and ice measurements show that both the Greenland and Arctic ice sheets are losing mass at an increasing rate. Glaciers in other parts of the world have been melting at an increased rate since 1990. Summer time melting of Arctic sea-ice has accelerated since 2007 far beyond any of the IPCC predictions; averaging 40% less than average IPCC predictions.

Satellite measurements of sea level rise also exceed IPCC predictions, rising 3.4 mm/yr over the past 15 years, about 80% above past IPCC predictions. At this rate, global sea level rise is likely to be twice as much as predicted by the IPCC, perhaps as much as 2 meters.

Rising temperatures are beginning to trigger positive feedback loops. It is believed that as one degree Celsius warming carries moderate risks of passing large scale tipping points and three degrees Celsius warming would bring substantial or severe risks.

The 2005 drought in Western Amazonia resulted in a massive release of carbon, and event that is expected to become more common. If a lengthening of the dry season continues and droughts increase in frequency or severity, the system could reach a tipping point resulting in a dieback of up to 80 percent of the rainforest and its replacement by a savannah.

Farther north, the southern boundary of the permafrost zone has shifted northward over North America, as well as higher on the Tibetan plateau. Similar observations in Europe have noted permafrost thawing. As the permafrost melts, organic materials decay, producing methane. This feedback has not been accounted for in any of the IPCC projections.

Some of the most concerning regions and tipping points include the Greenland ice sheet which may be nearing a tipping point where its melting is irreversible. The West Antarctic ice sheet may also be nearing a melting tipping point.

The Indian summer monsoon is probably already being disrupted. Some future projections show a doubling of drought frequency within a decade.

Global CO2 emissions will have to peak by 2020 and then decline rapidly in order to avoid catastrophic climate change. The fact that they have been accelerating in recent years makes this is an even more daunting challenge.

Governments are moving at a slow pace at best on global warming. Achieving significant reductions will involve massive investment plus changes in public behavior that governments are reluctant to enforce. For those concerned about global warming, the lifeboat strategy is becoming more imperative as time goes on: developing local, self sufficient communities that can survive a low energy future, and can adapt to the changes that are coming.