2° is too much

By Global Warming
Today many governments and scientists agree that the world needs to keep below an average global temperature rise of 2°C (3.4°F) above pre-industrial times (circa 1800).

This takes into account that the world has already warmed by 0.7°C since pre-industrial times. The margin for manoeuvre becomes tighter.

The 2°C threshold is based on the best available science – the third assessment report of the Intergovernmental Panel on Climate Change (IPCC).

This threshold has been accepted by many governments, including the Prime ministers and Presidents of all 25 European Union member states.

The science

Over 2,000 scientists contributed to the IPCC Third Assessment Report published in 2001. The graph below shows at what temperature a warming world starts to become really dangerous.

The red line marks the 2°C threshold and has been added by WWF. It is the red line we must not cross. We need to keep world average temperatures below this mark to avoid catastrophic climate change.

The future is in our hands like never before – if we act now we can turn the tide and avoid dangerous climate change.

The difficult question is at what level CO2 concentrations in the atmosphere will have to peak – or be stabilized - to prevent 2°C being exceeded?

At ‘Avoiding Dangerous Climate Change’, a 3-day conference in the UK held in early 2004, Malte Meinshausen from ETH Zurich and others presented their assessment of this question.

If CO2 concentrations were to stay below 400ppm (parts per million), staying below 2°C would be likely (probability of exceeding 2°C ranges between 8% and 57%, depending on the model). However, given current energy and power infrastructures, it is very unlikely that we can keep concentrations that low.

A level of 550ppm is very unlikely to keep us below 2°C and could even mean overshooting 4°C. At 475ppm the prospect of staying below 2°C is still rather slim.

If 475ppm was the peak and a rapid decrease followed, by the year 2100, we have at least options to stabilise at a temperature 2°C higher than pre-industrial times.

Note: Current concentrations of CO2 are at over 380 ppm. These measurements include the effect of other greenhouse gases by attributing global warming values equivalent to CO2; greenhouse gas warming capacities are expressed in CO2 equivalents.

- - - -

Source:
Meinshausen, M, What does a 2°C target mean for greenhouse gas concentrations? In ‘Avoiding Dangerous Climate Change’, 2006, Cambridge University Press

WWF

Comments

Post a Comment

Popular posts from this blog

Temperature rises and extreme weather

By Global Warming
Heating up Fever is an early and usually reliable sign of illness – one of the first things any doctor looks for when a person is not feeling well. Our planet has a fever Specialist researchers at Britain's University of East Anglia have put together all the available data to produce a temperature chart for the last millennium. The warmest year on record was 1998, while the ten warmest years globally have all occurred in the last decade and half. The Intergovernmental Panel on Climate Change (IPCC) has also said that most of the observed warming over the last 50 years "is likely to have been due to the increase in greenhouse gas concentrations." The most significant of these gases is carbon dioxide (CO 2 ). And the single biggest source of it – 37% of all emissions worldwide – is the carbon-rich coal burnt in power plants. The global average temperature has increased by about 0.7°C in the last hundred years, according to the European Env...
Read more

Gulf Stream

By Global Warming
Of all the ocean currents, the Gulf Stream is one of the strongest. It brings warmth to Europe and North America. In fact, average annual temperature in north-west Europe is about 9°C above the average for this latitude because of the Gulf Stream. How does it work? Surface water in the north Atlantic is cooled by winds from the Arctic. It becomes more salty and more dense, which makes it sink to the ocean floor. The cold water then moves towards the equator where it slowly warms. To replace all this cold water, the Gulf Stream moves warm water from the Gulf of Mexico to the North Atlantic. Could global warming affect the Gulf Stream? When the last Ice Age ended (10,000 years ago) and huge amounts of ice melted, the water in the North Atlantic became less salty because of all this new freshwater. As a result, the ocean water in the North Atlantic was less dense, and did not sink. This caused the Gulf Stream to shut down. Temperatures in north-west Europe fell by 5°C in just a few decade...
Read more

Nature at Risk

By Global Warming
Animals and plants are under increasing threat from climate change. Human-induced climate change has already sounded the death knell for its first victims. The golden toad (Bufo periglenes) and the harlequin frog (Atelopus varius) of Costa Rica have disappeared as a direct result of global warming. Species are under threat in more than one way. Irreversible changes to ecosystems and animals As climate change wreaks its havoc across the globe, ecosystems could disappear altogether, or they may undergo serious and irreversible changes, such as those happening to coral reefs. Warming affects cold seas and polar communities as well: Polar bears in the Hudson Bay area of Canada are losing weight and getting less fit because the ice breaks up 2 weeks earlier in spring, robbing them of 2 weeks’ hunting. Fish stocks that used to stay in Cornwall in south England have moved as far north as the Shetland Islands. As average temperature increases, optimum habitat for many species will move higher...
Read more