New evidence is emerging on almost a weekly basis to link rises in man-made carbon dioxide in the atmosphere with the real and immediate threat that global climate change presents to our environment, people and communities.
Earlier this year, scientists published a study in the journal Nature that indicated that many plant and animal species are unlikely to survive climate change. Their analyses suggest that 15 percent to 37 percent of a sample of 1,103 land plants and animals would eventually become extinct as a result of climate changes expected by 2050.
And earlier this month, 300 scientists contributing to the Arctic climate impacts assessment warned that Arctic temperatures have risen by almost twice the global average over the past 50 years. This increase looks set to continue, with a further rise of between 4℃ and 7℃ possible by 2100.
The rise in Arctic temperatures is already impacting heavily on people and wildlife. Buildings from Russia to Canada have collapsed because of subsidence linked to thawing permafrost, and mammals such as polar bears and seals have been affected.
We know the global temperature has now risen by between 0.6℃ and 0.7℃ over the past century. Globally, the 1990s were the hottest decade, and 1998 was the hottest year since our records began in 1861. Moreover, the seven hottest years since 1861 all fell in the 1990s.
Around the world, glaciers are thinning and in retreat and sea levels are rising. During the 20th century, the sea level rose by 10cm to 20cm, and global snow cover has diminished by 10 percent since the 1960s.
Carbon dioxide levels are at their highest ever and set to increase. Natural effects alone, such as El Nino, could not have caused that increase. It is a result of man's action in burning up reserves of carbon at a rate that has never been exceeded before.
The atmospheric concentration of carbon dioxide has risen by almost 30 percent since the Industrial Revolution. Both the current concentration of about 379 parts per million (ppm) -- compared with 280ppm in the pre-industrial era -- and the current rate of increase of approximately 2ppm annually, are the highest since the last ice age.
The planet has not experienced comparable concentrations for at least 740,000 years -- and probably for many millions of years.
The Greenland ice sheet was retreating at a rate of around 1m a year in 2001, according to a NASA study. The latest study indicates it is moving back at about 10m a year. If the Greenland ice sheet were to melt, the sea level would rise by between 6m and 7m. That would create a major problem for coastal cities.
More intense rainfall events are expected to be a feature of climate change. If we do not prepare for these, the impacts could be significant. We already know the power and devastation that can be unleashed on our communities by extreme weather. In 2002, severe floods in Europe caused 37 deaths and had an estimated direct cost of US$16 billion.
According to the Association of British Insurers, 2000 was the wettest UK autumn for almost 300 years, with heavy rainfall leading to damage to 10,000 properties and nearly ?1 billion in insurance claims.
During the heatwave last year, 14,000 people died in France, while the death toll across Europe reached 30,000. This was the worst natural disaster in Europe in 50 years. Statistical analyses show, with 90 percent certainty, that roughly half of the severity of this hot summer can be attributed to global warming.