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1. What's Happening to Global Climate?

We're Changing Our Climate! Who Can Doubt It?

- B Y SIMON RETALLACK AND PETER BUNYARD -

The reality of human-induced climate change is now beyond question. While

certain vested interests and elements of the mass media like creating the impression of an ongoing debate, in truth, there is an overwhelming consensus

among scientists that human-induced climate change is happening.

The facts are indisputable. First, take the physics of gases such as carbon dioxide, methane, nitrous oxide and CFCs: they are radiatively active - they trap heat in the Earth's atmosphere. So, i f you put heat-trapping gases up into the atmos­ phere, through the burning of fossil fuels and the destruction of natural forests, you will trap heat. And that, of course, is precisely what humans have been doing with particular zeal since the indus­ trial revolution of the mid-19th century - no one denies that emis­ sions and consequently atmospheric greenhouse concentrations have been soaring for decades. As a consequence, it should come as no surprise that humans are heating the planet.

Official confirmation came in 1995, when the Inter-Govern­ mental Panel on Climate Change (IPCC) - the official scientific body established in 1988 by the UN to investigate climate change - published its Second Assessment Report, written and reviewed by some 2,000 scientists. It stated that "the balance of evidence suggests there is a discernible human influence on global cli­ mate."1

A consensus now undeniably exists that human-induced cli­ mate change is real and has to be tackled. In the words of the then Chair of the IPCC, Bert Bolin, "Al l the summaries [of the IPCC] have been agreed at the plenary meetings without dissent and none of us has received any subsequent letters of complaint from scien­ tists regarding the final version. The process provides justification for the description of substantial scientific consensus."2 As James McCarthy, chairman of the Scientific Committee for the Interna­ tional Biosphere Programme, moreover, declares: "There is no debate among any statured scientists [i.e. those currently engaged in relevant research and whose work has been published in the refereed scientific journals] about what is happening."3

A consensus now undeniably exists that human-induced climate change is real and has to be tackled.

The relationship between greenhouse gases and climate that has now been established is supported by evidence from isotopic studies of ice-core material from both Antarctica and Greenland. The evidence shows that every period of global cooling has gone hand-in-hand with a drop in both carbon dioxide and methane in the atmosphere, and every time the planet has thawed, a surge has taken place in those same gases.4

The climat e i s changing before our very eyes Rising temperatures are already the clearest sign of climate change. So far, according to the IPCC, global average tempera­ tures have risen 0.6°C above the pre-industrial average. Nine of

the hottest years on record have occurred since 1988; six of the first eight months of 1998 were the warmest since records began in 1866; and July 1998 was the hottest month ever. According to the IPCC's latest coupled ocean-atmosphere models, i f emissions continued to rise on current trends, greenhouse gas concentrations would reach double pre-industrial levels - higher than for several million years - by 2080. Were this so, we would see a global aver­ age increase of 2.5°C, with perhaps 4°C over land masses, partic­ ularly in the northern high latitudes, 3°C to 4°C over parts of the Arctic or Antarctic, and possibly substantial regional variations from the global average. I f the increases in temperature seem modest, it should be noted that a 3°C cooling brought on the most recent ice age. What is more, the climatologists of the IPCC pre­ dict that i f emissions continued to rise on current trends, a second doubling of pre-industrial levels of CO2 could lead to a cata­ strophic rise of around 10°C. Even these predictions may under­ state the speed and scale of change (see 'Misreading the Models', p75). The destabilising effect of planetary warming upon our climate systems is already being felt. Over the past decade, worldwide, we have seen virtually every climate record broken since reliable record-taking began a century ago.

The implications for life are immense. With higher tempera­ tures, there is more energy driving the Earth's climatic systems, which in turn causes more violent weather events. Severe storms, floods, droughts, dust storms, sea surges, crumbling coastlines, salt water intrusion of groundwater, failing crops, dying forests, the inundation of low-lying islands, and the spread of endemic dis­ eases such as malaria, dengue fever and schistosomiasis is on the cards i f the consumption of fossil fuels is not phased out. Agricul­ ture worldwide would face severe disruption and economies could tumble. There would also be millions upon millions of environ­ mental refugees - people fleeing from the intruding sea, or equal­ ly from the deserts they have left in their wake after stripping the land of its vegetation. Those are the prospects and scientific advis­ ers to the UK government are warning that millions will die worldwide because of the processes of global warming that have already been unleashed.

The destabilising effect of planetary warming upon our climate systems is already being felt. Over the past decade, worldwide, we have seen virtually every climate record broken since reliable record-taking began a century ago. There has been a marked increase in the frequency and intensity of droughts, heat-waves,

60

The Ecologist, Vol. 29, No 2, March/April 1999