Global warming worse than feared
A unanimous report of hundreds of scientists from more than 100 countries has affirmed, on the basis of new and stronger evidence, that most of the warming over the last 50 years has been caused by human activities.
Chee Yoke Ling
A NEW report which incorporates the research findings of hundreds of scientists working on climate change and which attempts to reconstruct climate data for the past thousand years has presented some alarming data and projections.
‘In light of new evidence and taking into account the remaining uncertainties, most of the observed warming over the last 50 years is likely to have been due to the increase in greenhouse gas concentrations,’ says the report. ‘Likely’ is defined by the report as a 66 to 90% chance.
These scientists, who met in Shanghai, China on 17-20 January, are from the Intergovernmental Panel on Climate Change (IPCC), established by the World Meteorological Organisation and the UN Environment Programme (UNEP) in 1988. The IPCC is supposed to provide policy makers with ‘authoritative and up-to-date scientific information’.
Their First Assessment Report in 1990 confirmed that climate change is a threat and formed the basis for the UN treaty.
The Second Assessment Report in 1995 linked human activities to climate change, and projected that average global surface temperatures would rise by 1 to 3.5 degree C by 2100.
The latest report of the IPCC scientific assessment working group which was released in Shanghai is alarming because new data and better assessment techniques led to a more devastating projection. Warming is now expected to go up between 1.4 and 5.8 degree C between 1990 and 2100.
Among the findings are:
· The global average surface temperature rose by about 0.6 degree C over the 20th century. The 1990s was the warmest decade, and 1998 the warmest year since 1861, when instruments were first used to record temperatures.
· The global average surface temperature is projected to increase by 1.4 to 5.8 degree C between 1990 and 2100. This is far more than the projection in the 1995 assessment of a 1 to 3.5 degree C temperature rise.
· Model simulations reveal that warming in the northern regions of North America, and northern and central Asia will be 40% more than the global average.
· Snow cover has dropped by about 10% since the 1960s. There was a widespread retreat of mountain glaciers outside the polar regions during the 20th century. In the Arctic, sea-ice thickness is likely to have declined by about 40% in recent decades during late summer to early autumn. More decrease is projected for both snow cover and sea-ice extent.
· The global average sea level rose between 0.1 and 0.2 metres during the 20th century, while global ocean heat content has gone up since the late 1950s, the period for which data on sub-surface ocean temperatures have been available. There is a projected rise of another 0.09 to 0.88 metres between 1990 and 2100.
· Precipitation in the northern hemisphere went up by 0.5 to 1% every decade in the 20th century. In tropical land areas, rainfall has risen by 0.2 to 0.3% per decade.
· In parts of Asia and Africa, the frequency and intensity of droughts have increased in recent years.
· Human activities will continue to change the climate in the 21st century, with CO2 emissions from fossil fuel burning as the dominant influence.
· To stabilise CO2 concentrations in the atmosphere at 450 ppm, the IPCC report said that human-induced emissions will have to drop below 1990 levels within a few decades. (CO2 made up over 80% of the greenhouse gases from developed countries in 1995. Of this, 97% was from fuel combustion.)
The IPCC exists to provide governments with scientific assessments of worldwide research on climate change. Its approach is highly conservative, and undergoes scrutiny by governments as well as hundreds of scientists. By no means at the cutting edge of climate research, the IPCC reports nevertheless represent dominant consensus for policy makers.
More than 100 countries are members of the IPCC, which has three Working Groups.
Working Group I on scientific assessment released its report in Shanghai in January. The 1,000-page draft volume entitled ‘Scientific Assessment of Climate Change’ was accepted by several hundred expert and government reviewers.
It is the work of 123 lead authors, 516 contributing authors, 21 review editors and 300 expert reviewers. In Shanghai, about 100 member countries of the IPCC were present.
The Working Group II report on impacts, adaptation and vulnerability was finalised in Geneva from 14-16 February.
The Working Group III report on the mitigation of climate change will be finalised in Accra from 28 February to 3 March.
All three reports will be accepted by the full IPCC Plenary when it meets in Nairobi from 4-6 April, becoming the IPCC Third Assessment Report. It will have a significant role when governments meet again later in the year to renew the Kyoto Protocol negotiations that were suspended last November.
Meanwhile, the destabilisation of climate continues.
Greenhouse gases such as CO2 and methane are long-lived. Once they are emitted, they have a lasting effect on the atmosphere and climate. For example, several centuries after CO2 is released, about 25% of the resulting increase in CO2 concentration is still in the atmosphere.
So, even if there is stabilisation of greenhouse gas concentrations at present levels (already more than the 1990 level set by the UN agreements as the level to achieve), the damage will already have been done. The last 100 years of human activity have triggered climate change, with all its adverse impacts, which the IPCC report warns ‘will persist for many centuries’.
If the world continues with more ‘business as usual’, as in the last 10 years, there will be a temperature rise of several degrees every century. The result would be catastrophic beyond imagination.