Climate change – the latest analysis

Now, though, the UK government acknowledges that the climate is changing, and politicians are beginning to talk about "living with climate change". As well as accepting the inevitable changes that lie ahead, they seem to have absorbed some of the science behind global warming.

Without the global warming effect of natural gases in the atmosphere, the earth's temperature would be about 33ºC cooler. Not simply chilly, the earth would be uninhabitable. However, increasing the concentration of human-made greenhouse emissions seems to be raising temperatures. 1990-1999 was the warmest decade on record – about 0·6ºC warmer than at the end of the last century.

The International Panel on Climate Change (IPCC) suggests that average surface temperatures around the world have risen 1ºC since 1860. The UK's foremost research body for climate change, the Hadley Centre, says surface temperatures will rise another 3ºC by 2100. More worrying, land temperatures will rise about twice as fast as sea surface temperatures because the deep ocean absorbs some of the heat at the surface.

What does this mean for buildings in the UK? "Annual mean temperatures by the middle of the next century...[will be] about 2ºC higher in the south and 1·6ºC higher in the north of the UK," says the Hadley Centre. This will inevitably put greater pressure on air conditioning systems, and could threaten natural cooling strategies. Night cooling, in particular, is likely to be less effective because there will be "a big increase" in the number of days when night temperatures poke above 20ºC.

A spokesperson from the Hadley Centre said: "18·8ºC is the highest night-time temperature on record for central England, but our greenhouse gas model shows there will be a 5% probability of reaching 20ºC [in June, July and August by 2100]."

However, the Hadley Centre reckons that some fears about climate change are over the top. Scaremongering that the UK could enter "the grip of an ice age" because of changes to the Gulf Stream are unfounded, it claims. "Although the input of heat to north-west Europe may be reduced due to changes in the Gulf Stream, the direct heating from greenhouse gases in the atmosphere more than offsets this." Winter heating loads are not, therefore, likely to mushroom as some people had feared.

One of the Hadley Centre's findings could be read as a damning indictment of the Kyoto Protocol targets. Assuming that developed countries honour their commitments under the Protocol, as well as reducing their emissions year-on-year from 2015 onwards, modelling suggests that this will only restrain mean temperature rises by about 0·4ºC (double for land temperatures).

The government counters scepticism about the impact of its drive to cut CO₂ emissions using science and statistics. There are currently about 325 parts per million (ppm) of COM² in the atmosphere – a figure that is rising. The government claims stabilising atmospheric CO₂ at 550 ppm will "substantially reduce the magnitude of changes and impacts [of climate change] over the next century". The government also holds that this would delay many of the impacts by 50-100 years.

However, the changing global temperatures will have catastrophic effects on the way people live. Sea level rise has hit newspaper headlines across the globe, and some countries now fear for their existence if the predicted rises materialise.

A sea-change in Antarctica?

The IPCC says that the mean sea level has risen between 10 and 25 cm over the last 100 years. The sea level will continue to rise because sea water expands as it gets warmer, because glaciers will melt, and because the Greenland and Antarctic ice sheets will change.

The IPCC says that there is a lot of uncertainty about how the Antarctic ice sheet will react as a result of global warming.

There is a possibility it could suddenly collapse, creating a major sea level rise, but the IPCC says the risk of this happening before 2100 is "low". In fact, the IPCC considers that more snow on Antarctica will actually help to relieve some of the pressure on sea level rise – by trapping more water on land as snow.

The Hadley Centre says the most likely scale of global sea-level rise will be from 40 to 60 cm by 2100, depending on how CO₂ emissions change over the decades ahead. Whatever the magnitude of the rise though, some human adaptation to sea-level rise will be essential, it says.

Another frightening long-term prediction is that tropical forests in South America and Africa will die back near the end of the next century. This means that a major sink for CO₂ will be lost, so accelerating the rate of climate change. Consequently, climate change will be even higher than current predictions.

So what progress have we made so far in cutting CO₂? The latest round of international climate change talks – in Bonn in November 1999 – brought together top ministers and civil servants from 166 governments.

As ever, the Kyoto Protocol dominated discussions. This will place a legal bind on developed countries to cut emissions of the six human-made greenhouse gases by 5·2% compared to 1990, by 2008-2012.

The ministers hesitantly agreed to sort out the remaining technical details of the protocol by November this year. This should make it possible to bring it into force during 2002 – ten years after the UN conference in Rio that first put climate change on the international agenda. However, the protocol only comes into force when at least 55 countries have ratified it, including at least enough developed countries to make up 55% of CO₂ emissions. So far, only 16 governments have ratified, all of them from countries in the developing world. The US stance is critical, and current indications are that it will miss its target, making it politically difficult to ratify the protocol. Indeed, the US economy is currently overshooting its 1990 emissions by a massive 11% – 535 000 million tonnes of CO₂, or more than the entire annual UK output.

The next chapter of climate change talks starts this February in the Netherlands. Here, among other things, ministers intend to decide what constitutes a dangerous temperature rise.

Looking closer to home, the latest estimates suggest that the UK will easily meet its first base commitment of stabilising CO₂ emissions at 1990 levels by 2000. The Advisory Committee on Business and the Environment believes the government's manifesto objective of cutting CO₂ emissions by a fifth – 40-50 mega tonnes of carbon (MtC) – by 2010 is also possible.

To ensure the reductions materialise, the Committee recommends: