Priorities: Climate Change

Priority areas in global warming

According to the IPCC report published 2 Feb, 2007, there is evidence that the higher temperatures of the last half century are unusual compared with the at least the previous 1,300 years. As greenhouse gas levels have risen so have temperatures - global average air and ocean temperatures have been increasing and there has been widespread melting of snow and ice.

Eleven of the last 12 years have ranked among the 12 warmest years since records began in 1850, and as a result, the 100-year trend in temperatures has been adjusted upwards since the 2001 report, from an increase of 0.6C to 0.74C by the end of 2005. Much of the increase was recorded over the last 50 years, when the temperature increased by an average of 0.13C a decade - almost twice as fast as over the previous 100 years.

Research shows that the ocean has been absorbing more than 80% of the extra heat, causing water to expand and sea levels to rise. Between 1961 and 2003, the IPCC says, the global average sea level rose by an average of 1.8mm a year. And between 1993 and 2003 it was rising at a rate of 3.1mm a year. Whether this is a blip in the long-term trend, or an increase in the long-term outlook is unclear, but scientists are confident that sea levels rose much more quickly last century than in the 1800s.

Average Arctic temperatures have increased at almost twice the global average rate over the past 100 years, and the ice has shrunk by 2.7% each decade. Since 1900, the area covered by frozen ground has decreased by about 7%.

Elsewhere, more intense and longer droughts have been seen over wider areas since the 1970s, particularly in the tropics and sub-tropics, and in the North Atlantic there has been an increase in the incidence of typhoons and hurricanes.

Dramatic flips in the way ecosystems absorb carbon dioxide will see oceans and vast swaths of land falter in their ability to draw up the greenhouse gas, allowing it to build up in the atmosphere and cause more warming. The phenomenon is known as a positive feedback - where global warming drives changes in ecosystems that themselves cause more heating.

The latest IPCC report for the first time includes climate models that take into account two other ecological feedback mechanisms that accelerate global warming: the ability of the oceans and land to absorb carbon.

"The oceans and the soils and trees absorb a half of the carbon dioxide released into the atmosphere from human activity. With climate change, they will get worse and worse at doing that, so more of our human emissions of carbon dioxide will remain in the atmosphere
As the world warms up the oceans become less able to dissolve carbon dioxide. Warmer oceans are also having an adverse effect on carbon-absorbing marine phytoplankton, the organisms that lie at the very bottom of the aquatic food chain. As warming continues scientists fear that phytoplankton will begin to die off, creating a positive feedback cycle where warmer oceans release more carbon which in turn leads to more warming.

At the same time carbon dioxide which now fertilises soils and boosts the growth of forests and other plants will reach saturation point, so the land's ability to soak up carbon dioxide will stall. As temperatures rise even further many plants will become stressed by drought conditions and microbes in the soil will start breaking down organic matter from dead plants faster, meaning large areas of land will begin emitting carbon dioxide instead of acting as an overall sink for the gas.

Signs that soils were beginning to become part of the problem of global warming emerged in 2005 when researchers discovered that a vast expanse of western Siberia was undergoing an unprecedented thaw. The region, the largest frozen peat bog in the world, covering an area the size of France and Germany combined, had begun to melt for the first time since it formed 11,000 years ago at the end of the last ice age.

The team, from Tomsk State and Oxford universities believe the million square kilometre peat bog could begin to release billions of tonnes of methane locked up in the soils. Methane is a greenhouse gas 20 times more potent than carbon dioxide.

The team found that even if methane seeped from the peat bog over the next 100 years it would add 700m tonnes of carbon into the atmosphere every year, roughly the same that is released annually from the world's wetlands and agriculture. It would effectively double the atmospheric levels of the gas, leading to a 10% to 25% increase in global warming.

Source: Ian Sample,Why the news about warming is worse than we thought: feedback, Guardian, Feb 3, 2007, http://environment.guardian.co.uk/climatechange/story/0,,2005119,00.html

Livestock’s Contribution to Global Warming
Transport is a tiny component of agriculture’s worldwide contribution to greenhouse gas emissions. One study found that livestock – predominantly cattle – are responsible for an astonishing proportion of global warming gases - 18 per cent of the total, to be precise (1).
Seventy per cent of all agricultural land is used to raise animals – that’s a third of the land surface of the entire planet. What’s more, over a third of all cereal production goes to feed those animals (FAO) (2). Most deforested land is used for pasture and the UN reckons the carbon released in the process takes the carbon cost of livestock up to the equivalent of 2.7 billion tonnes of carbon dioxide. That’s around seven per cent of all the greenhouse gases emitted by man.

Another global warming gas - nitrous oxide is way more potent than even methane with 296 times the global warming power of carbon dioxide. Sixty five per cent of human related emissions of nitrous oxide are from the nitrogen in animal manure.

(1) Ethical Man - Justin Rowlatt, BBC News Night
http://www.bbc.co.uk/blogs/newsnight/2007/02/
meet_daisy_the_cow_global_climates_enemy_number_on.html

(2) FAO, “Livestock’s Long Shadow”, 2006



Transport In Britain

The Oxford researchers found that 61 per cent of all travel emissions came from individuals in the top 20 per cent of 'emitters', while only 1 per cent of emissions came from those in the bottom 20 per cent.This high emitters group is mostly made up of employed men in high income groups (earning over £40,000 per year). And across the board, people in high income groups have an average climate change impact of 11.3 tonnes of carbon dioxide - twice the national average. This means they earn around four times as much as low earners and produce on average almost four times as much carbon dioxide emissions.

Professor John Preston, said:"The UK is facing tough choices on how to lower greenhouse gas emissions in response to climate change. The transport sector contributes 26 per cent of UK carbon emissions and is the only major sector in which emissions are predicted to rise in the period till 2020. Transport is thus a priority area for government policy. This research helps us understand the extent to which individuals' travel patterns, their location and their social class make an impact on climate change through the carbon dioxide emissions created by their transport use."(ESRC Society Today).

In Oxford, the allowance is higher, at five tonnes, but so are the penalties for overshooting, at 5p per kilo. Catherine Bottrill, a researcher at Oxford University's Environmental Change Institute and a member of the Oxford Crag, says the 10-strong group's emissions ranged from three to 14 tonnes a year ago.

Study showed that air travel accounted for 70% of the sector's climate change impact, while cars were responsible for 25%, and public transport for 3.5%. The study concluded that current UK green tax plans are unlikely to curb the growth in greenhouse gas emissions from travel. High-income groups, whose emissions were twice the national average, would absorb any price increase rather than change their travel habits, said Oxford University researcher Christian Brand. Less direct or modestly used fiscal instruments such as moderate petrol or aviation fuel-price increases are less likely to have an effect on the more wealthy sub-sector of the travelling community, he said.


Source: http://www.tsu.ox.ac.uk/research/oxontravel