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1827: French polymath Jean-Baptiste Fourier suggests the
existence of an atmospheric effect keeping the Earth warmer than it would
otherwise be. He also uses the analogy of a greenhouse
1863: Irish scientist John Tyndall publishes paper describing how
water vapour can be a greenhouse gas
1890s: Swedish scientist Svante Arrhenius and an American, P.C.
Chamberlain, independently consider the problems that might be caused by CO2
building up in the atmosphere. Both scientists realise that the burning of
fossil fuels could lead to global warming, but neither suspect the process
might already have started
1890s to 1940: Average surface air temperatures increase by about
0.25 °C. Some scientist see the American Dust Bowl as a sign of the
greenhouse effect at work
1940 to 1970: Worldwide cooling of 0.2 °C. Scientific interest in
greenhouse effect wanes. Some climatologists predict a new ice age
1957: US oceanographer Roger Revelle warns that people are
conducting a "large-scale geophysical experiment" on the planet
by releasing greenhouse gases. Colleague David Keeling sets up first
continuous monitoring of CO2 levels in the atmosphere.
Immediately Keeling finds regular year-on-year rise
1970s: Series of studies by the US Department of Energy increases
concerns about future global warming
1979: First World Climate Conference adopts climate change as
major issue and calls on governments "to foresee and prevent potential
man-made changes in climate"
1985: First major international conference on the greenhouse
effect at Villach, Austria, warns that greenhouse gases will "in the
first half of the next century, cause a rise of global mean temperature
which is greater than any in man's history". This could cause sea
levels to rise by up to a metre, researchers say. Conference also reports
that gases other than CO2, such as methane, ozone, CFCs and
nitrous oxide, will also contribute to warming
1987: Warmest year on record. The 1980s turn out to be the
warmest decade, with seven of the eight warmest years recorded up to 1990.
Even the coldest years in the 1980s were warmer than the warmest years of
the 1880s
1988: Global warming attracts worldwide headlines after
scientists at Congressional hearings in Washington DC blame major US
drought on its influence. Meeting of climate scientists in Toronto
subsequently calls for 20 per cent cuts in global CO2 emissions
by the year 2005. UN sets up the Intergovernmental Panel on Climate Change
(IPCC) to analyse and report on scientific findings
1990: The first report of the IPCC finds that the planet has
warmed by 0.5 °C in the past century. IPCC warns that only strong measures
to halt rising greenhouse gas emissions will prevent serious global
warming. Provides scientific clout for UN negotiations for a climate
convention. Negotiations begin after the UN General Assembly in December
1991: Mount Pinatubo erupts in the Philippines, throwing debris
into the stratosphere that shields the Earth from solar energy, which helps
interrupt the warming trend. Average temperatures drop for two years before
rising again. Scientists point out that this event shows how sensitive
global temperatures are to disruption
1992: Climate Change Convention, signed by 154 nations in Rio,
agrees to prevent "dangerous" warming from greenhouse gases and
sets initial target of reducing emissions from industrialised countries to
1990 levels by the year 2000
1994: The Alliance of Small Island States - many of whom fear
they will disappear beneath the waves as sea levels rise - adopt demand for
20 per cent cuts in emissions by the year 2005. This, they say, will cap
sea-level rise at 20 centimetres
1995: Hottest year yet. In March, the Berlin Mandate is agreed by
signatories at the first full meeting of the Climate Change Convention in
Berlin. Industrialised nations agree on the need to negotiate real cuts in
their emissions, to be concluded by the end of 1997
In November, the IPCC casts caution to the winds and agrees that current
warming "is unlikely to be entirely natural in origin" and that
"the balance of evidence suggests a discernible human influence on
global climate". Report predicts that, under a "business as
usual" scenario, global warming by the year 2100 will be between 1 °C
and 3.5 °C
1996: At the second meeting of the Climate Change Convention, the
US agrees for the first time to legally binding emissions targets and sides
with the IPCC against influential "sceptical" scientists. After a
four-year pause, global emissions of CO2 resume steep climb, and
scientists warn that most industrialised countries will not meet Rio
agreement to stabilise emissions at 1990 levels by the year 2000
1997: Kyoto Protocol agrees legally binding emissions cuts for
industrialised nations, averaging 5.4 per cent, to be met by 2010. The
meeting also adopts a series of flexibility measures, allowing countries to
meet their targets partly by trading emissions permits, establishing carbon
sinks such as forests to soak up emissions, and by investing in other
countries. The precise rules are left for further negotiations. Meanwhile,
the US government says it will not ratify the agreement unless it sees
evidence of "meaningful participation" in reducing emissions from
developing countries
1998: Follow-up negotiations in Buenos Aires fail to resolve disputes
over the Kyoto "rule book", but agree on a deadline for
resolution by the end of 2000. 1998 is the hottest year in the hottest
decade of the hottest century of the millennium
2000: Scientist re-assess likely future emissions and warn that,
if things go badly, the world could warm by 6 °C within a century. Series
of major floods around the world reinforce fears that global warming is
raising the risk of extreme weather events. But in November, crunch talks
held in The Hague to finalise the "Kyoto rule book" fail to reach
agreement after EU and US fall out. Decisions postponed until at least May
2001.
2001: The new US president, George W. Bush, renounces the Kyoto
Protocol because he believes it will damage the US economy. After some
hesitation, other nations agree to go ahead without him. Talks in Bonn in
July and Marrakech in November finally conclude the fine print of the
protocol. Analysts say that loopholes have pegged promised cuts in
emissions from rich-nation signatories to 1.5 per cent, compared to the
Kyoto promise of 5.4 per cent. Signatory nations urged to ratify the
protocol in their national legislatures in time for it to come into force
before the end of 2002.