Transcript No Slide Title
Climate change – why bother
David Archer
Green Ovingham
Outline of slide show
• • • • • The scientific basis of climate change Evidence from global observations – The rise in temperature – The rise in sea level – The loss of Arctic sea ice – Retreat of glaciers – Droughts and floods Local evidence of climate change Global and local risks A response to sceptics
The greenhouse effect
We live in a Goldilocks world: neither too hot, too cold but just right. The normal greenhouse effect keeps it that way (otherwise the worlds average temperature would be -18C) Adding CO2 and other greenhouse gases pumps up the temperature
The scientific basis of climate change 1
Where better to start than in our back garden – in the greenhouse. Glass in the greenhouse allows incoming solar radiation (light) to pass through but holds back the outgoing heat radiation - so the inside temperature gets warmer. Plants thriving in winter in the greenhouse
The scientific basis of climate change 2
Carbon dioxide (CO 2 ), methane and several other ‘greenhouse’ gases work in the same way. The main source of CO
2
is the burning of fossil fuels in heating, lighting transport and industry.
The main source of methane is the belching of cows! But otherwise also from fossil fuel production and landfill.
The scientific basis of climate change 3
Carbon dioxide (CO from a pre-industrial million 2 ) in the atmosphere has risen average of 280 parts per million to 380 parts per Methane (CH 4 ) has more than doubled since pre industrial age. It is 20 times more effective than carbon dioxide as a greenhouse gas but at a much lower concentration
The scientific basis of climate change 4
How long have we known about the effects of CO 2 ?
• • • The principle of the effect of CO 2 on global climate was first established by the Swedish scientist Arrhenius in the 1890s. He calculated that doubling of CO2 in the atmosphere would cause global temperature to rise by 5 to 6 o C.
Present computer models suggest rather less but also include variations in the sun’s activity, absorption of CO 2 by the oceans and loss of polar ice.
Evidence from global observations The rise in air temperature 1
Global temperature has been rising steadily since 1960 The highest year for global temperature was 1998; In spite of our cold winters 2010 was second highest globally
Global temperature is now at its highest for more than 1000 years This is the Mann Hockey Stick graph disputed but still gives a reasonable general picture
Evidence from global observations The rise in air temperature 2
Evidence from global observations The rise in ocean surface temperature
Red shows an increase
Evidence from global observations The rise in sea level
Sea level is rising both as a result of melting of glaciers and with the water expanding at a higher temperature.
Satellites show recent global average sea-level rise (3.4 mm/yr over the past 15 years)to be 80% above past IPCC predictions
Sea level change during 1970-2010.
Evidence from global observations The decline of Arctic Sea ice 1
The change in Arctic sea ice between September 1979 and September 2005. Melting of Arctic sea-ice has accelerated far beyond the expectations of climate models; during 2007-2009 was about 40% less than earlier predictions from IPCC climate models.
Evidence from global observations The decline of Arctic Sea ice 2
Inuit struggling to move their boat through broken ice floes
Arctic sea ice freeze is occurring 3.5 weeks later than it did in the 1960s while the break up is occurring 2.5 weeks earlier. Changes threaten Arctic ecosystems including the polar bear and livelihoods of Inuit.
Evidence from global observations The melting of glaciers 1
The total melt area of the Greenland ice sheet increased by 30% between 1979 and 2008 with the most extreme melt in 2007.
Evidence from global observations The melting of glaciers 2
Glacier retreat in the Alps over more than a century. Retreat has accelerated in the last 20 years
Evidence from global observations The melting of glaciers 3
The glaciers on Kilimanjaro have almost gone (These views in 1969) With a few exceptions glaciers elsewhere are also retreating.
This includes the Alps, the Andes, the Rockies and most of the Himalaya. (Glaciers in the central Himalaya are predominantly retreating but not at the rate stated by IPCC)
10 9.5
9 8.5
8 7.5
7
Evidence from local observations 1 Annual temperature at Durham (1961-2005)
y = 0.0309x + 8.0889
R 2 = 0.4791
Steady upward rise of 0.3
° C per decade (1.4
° C in 45 years)
Evidence from local observations 2 Seasonal and annual temperature rise °C/decade
Durham
Annual Dec-Feb Mar-May Jun-Aug Sep-Nov 1961 - 2005 1982 - 2005 0.31
0.40
0.50
0.69
0.31
0.32
0.18
0.56
0.44
0.37
The biggest seasonal rise is in winter (in spite of this year’s frost)
Do you remember the snow of 1979 and the frost of 1982?
Much worse than 2010!
Pennine snow 1979 Tees at Broken Scar, Darlington, Jan 1982 Frozen peat 1972
Risks - Some local implications of temperature rise Not all local effects are negative!
• • • • •
Decreasing frequency of snow Evapotranspiration and drying soil in summer Shifting storm tracks, more passing to the north?
Rainfall intensities increasing Increase in flood risk
• • • • •
Upward altitudinal and latitudinal shift in climate zones Agricultural operations – more frequent summer drought Hill farming – animals remain outdoors for longer in winter But serious changes in moorland ecology Warmer summers – more tourism?
Global risks Sea level rise
By 2100 more than 1 m (possibly 2 m) rise is expected. 160 million people worldwide live less than 1 metre above sea level. Large parts of Bangladesh will be affected.
Flat island states like the Maldives and Tuvalu will disappear.
Mass migration will affect us all.
Risks - Floods and droughts
. Warmer air is more energetic and can hold more moisture. In many places droughts and floods have become more extreme and more frequent .
Risks - climate change and flooding
There can be no doubt that climate is changing and changing in a way that will increase flood risk
Purnell, 2002 From the Christian Aid Magazine
Increasing flood risk is now recognised as the most important sectoral threat from climate change in most parts of the world
Fowler and Kilsby 2003
The autumn 2000 floods are a ‘wake-up call’ to the impacts of climate change
John Prescott Former Deputy Prime Minister
Response to Sceptics
There can be no denying the basic physics that increasing greenhouse gases cause global warming. We are likely to pay a heavy price if we keep emitting them.
Can we believe the IPCC after the so called ‘scandals’?
Yes we can with very limited exceptions. But climate campaigners have to be very careful not to exaggerate.
•
Climate has always changed and this is no different!
• • This is a half truth. Climate has always changed but we are now warmer than at any time during the last 1000 years. The recent increase in temperature cannot be explained by changes in solar output - but solar output has had severe past effects on global climate
Sustainability – the global dimension
• Local sustainability requires global sustainability – and vice versa • Most vulnerable to climate change are impoverished populations in marginal environments • Western lifestyle and demands influence Third World actions (Our demands are fuelling Chinese and Indian industrialisation and growth in greenhouse gases).
• Ethics and morality (as well as self interest) require that we take action to reduce impacts on the most vulnerable
The Limits to Growth
• The Earth is not infinite and cannot provide resources indefinitely for growing consumption.
• Exponential growth of population, consumption, resource and energy use, waste production is unsustainable.
• Unconstrained exponential growth is a cancer of the natural environment • New technologies extend but do not alter the tendency of the world system to grow and collapse • Anyone wishing to have a quiet life made a mistake being born in the late twentieth century.