Chapter 4: Adaptation and mitigation options

This chapter begins by saying that there are many adaptation options available which may be effective, but at the moment not enough is being done. It points out that a societies capacity to adapt is dynamic and depends on a number of factors including: natural and man-made capital, social networks and entitlements, human capital and institutions, governance, national income, health and technology.

The report goes on to say that there is 'substantial economic potential' for mitigating GHGs which may limit projected increases or reduce them to below current levels and that a variety of technologies and policies are needed to achieve this. It is mentioned that a reduction of 6GtCO2 eq/yr is possible in 2030 with no extra cost.

Page 15 includes a table of sectoral adaptation strategies, policies and constraints/opportunities. In the water sector, adaptation options include harvesting rainwater, conservation, water re-use, desalination, and irrigation efficiency. The implementation of these would require national water policies and integrated water resources management. The key constraints are financial, human resources and physical barriers. Opportunities exist for synergies with other sectors and integrated water resource management.

In terms of the agriculture sector, adaptation options include adjustment of planting dates and crop varieties; crop relocation; improved land management, e.g. erosion control and soil protection through tree planting. The implementation of these would require RD&D policies; institutional reform; land reform; training; capacity building; crop insurance; financial incentives. Key constraints include technology and finance; access to new crop varieties; markets. Opportunities include longer growing season in higher latitudes; revenues from new products.

The adaptation options available to the transportation sector include realignment and relocation of routes affected by climate change for example in coastal areas or areas of permafrost.

The energy sector requires the biggest overhaul. Adaptation options include strengthening overhead transmission and distribution infrastructure; underground cabling; energy efficiency; use of renewable sources; reduce dependency on single sources of energy. The following are needed in order to implement these adaptations: national energy policies, regulations, and fiscal and financial incentives to encourage use of alternative sources; incorporating climate change in design standards. Constraints include access to viable alternatives; financial and technological barriers; acceptance of new technologies. The opportunities include the stimulation of new technologies with the resulting economic boost; use of local resources.

Bringing global GHG emissions back to 2005 level by 2030 would require substantial shifts in investment patterns in energy, but would only cost about 5% extra. Investments in the usually energy plants (oil, coal, gas) now, would have long term impacts on GHG emissions due to the long life time of energy plants.

The report mentions two approaches to estimating mitigation potential. These are 'bottom up studies' which begin assessing from the sectoral perspective, and 'top down studies' which take a macro-economic position. Both approaches produce similar potential mitigation numbers.

Basically a wide variety of options are available to governments to create incentives to mitigate emissions. A price on carbon would be the first step, though fossil fuel exporting countries would likely suffer from this. International cooperation is an essential part of mitigation. The UNFCCC has been successful in setting up the Kyoto Protocol and creating an international market for carbon trading. These initiatives may lead the way for future policies to reduce emissions. Climate change policies support sustainable development and therefore should be integrated into national development programs.

Chapter 3: Projected climate change and its impacts

Chapter 3 deals with projected climate change and its impacts. This is probably the most interesting for the general public because everybody wants to know what will happen in the future.

It begins by saying that global GHG emissions will continue to increase even with the world's attempt at sustainable development. The IPCC Special Report on Emission Scenarios (SRES, 2000) predicts that emissions from fossil fuels will be most responsible for an increase in GHGs of around 25% - 90% as fossil fuels will be the dominant source of energy until 2030. It is predicted that this will lead to a 0.2 degree Celsius increase per decade, so the climate will essentially rise by another 1 degree within the next 50 years, which will take us to the 'safe limit' of 2 degrees warming (however, 2 degrees warming will severely impact Africa and small island nations). Here it points out an important positive feedback mechanism; that as the oceans warm, they become less capable of storing CO2 and therefore the concentration of atmospheric CO2 will increase, inducing further warming. Even if GHG emissions were stabilized at 2000 levels, an increase in temperature of 0.1 degrees Celsius per decade is expected.

In order to cover the range of possible future impacts of climate change, the IPCC has come up with a number of emission scenarios and the expected temperature increase relative to 1980 - 1999. Ultimately, the scenario our world takes will be determined by the actions of industry, politicians and people alike. The main scenarios are shown below:

• year 2000 constant: temperature increase of 0.3 degrees above 1980 - 1999
  
• B1 - GHGs increase from 40GTCO2 eq/yr to a peak of 55GTCO2 eq/yr in 2040 and then drop to 25GTCO2 eq/yr by 2100. This is the most optimistic scenario and is expected to cause an increase of 1.9 degrees by 2100 (above 1980-1999 average)
• A1B - GHGs increase from 40GTCO2 eq/yr to a peak of 75GTCO2 eq/yr in 2050 and then decrease to 60GTCO2 eq/yr by 2100. This leads to a temperature increase of 2.9 degrees by 2100.
  
• A2 - this is the scenario I believe is most likely, judging by the lack of will of Chinese and American political leaders and lack of consensus between the global north and south, and the general lack of a sense of urgency shown at Copenhagen COP15. Here, GHG emissions continue increase linearly reaching a peak in 2100 of almost 140GTCO2 eq/yr. Best estimates say this would lead to a temperature increase of around 3.4 degrees. Very dangerous situation!

Some systems and sectors will be particularly affected:

• ecosystems: in particular, tundra, boreal forest and mountain regions due to sensitivity to warming; Mediterranean ecosystems due to reduced rainfall; tropical rainforests where rainfall is expected to decrease; coastal mangroves and salt marshes due to multiple stresses (increased temp, sea level, changing wind and rainfall patterns); marine coral reefs due to multiple stresses
• water resources in dry regions at mid-latitudes and in the dry tropics
• agricultural output in low latitudes due to reduced rainfall
• low lying coastal areas due to increase sea level and increased threat from extreme weather events
• human health in poor countries

Regions that will be particularly affected:

• the arctic, because of high rates of warming (the arctic is expected to experience the highest temp increase)
• Africa, because it is poor and has a low adaptive capacity. Africa is expected to experience greater warming than many other parts of the globe
• small islands where there is high populations e.g. Maldives
• Asian and African mega-deltas, due to high population densities, low adaptive capacity, risk of storm surges and river floodings

Richer regions have a higher adaptive capacity, so will be less affected in human terms, but some segments of society (the poor, the elderly) will be.

Ocean Acidification

The ocean is becoming increasingly acidic due to absorption from the atmosphere which will have a negative impact on marine shell forming organisms, such as corals, which will impact those other organisms that depend on them. In short, no coral reefs would mean the oceans would be almost void of life.

Sea level rise

It is important to note that the scenarios for predicted sea level rise do not include the real possibility of rapid melt as temperatures continue to increase. This is a little unrealistic, but I guess the IPCC find it too difficult to calculate. So, the figure given here are very optimistic and for that reason I shown the upper ranges for each scenario:

• B1 - 1.8 degrees = 0.38 metres
• A1B - 2.8 degrees = 0.48 metres
• A2 - 3.4 degrees = 0.51 metres

The report also includes a summary table (table SPM2) that lists the possible regional impacts by continent. Table SPM3 lists the possible impacts on certain sectors, which includes both natural and human systems. These are definitely worth a look.

Warming could lead to some changes that are abrupt and/or irreversible. Here 'abrupt' means the melting of ice sheets on polar land, which is expected to happen over millennial time scales, but which may occur over centuries i.e. 'abrupt'. Irreversible impacts would include the loss of biodiversity, as it is expected that a 2.5 degree increase would wipe out 30% of species and a 3.5 degree increase is expected to wipe out 40 - 70% of all species.

Atlantic Ocean Circulation is expected to slow down over this century, but not stop completely. This means that Europe will continue to warm. The changes in the ocean circulation is expected to have corresponding impacts on marine ecosystems.

This chapter finishes by pointing out that due to the timescales on which the climate system operates, even if GHG emissions are stabilized, anthropogenic warming and sea level rise would continue for centuries. Though not specifically mentioned, I assume this is due to atmospheric residence times of GHGs.

Chapter 2: Causes of change

The second chapter deals with the causes of these changes. It begins by mentioning that the Earth's energy budget is changed by increases in GHGs and aerosols, land use change (deforestation) and variations in solar radiation. However, the main focus in not on variations in solar radiation but rather on anthropogenic GHG emissions. It is hard to believe that emissions of GHGs have increase by 70% since only 1970:

"Global GHG emissions due to human activities have

grown since pre-industrial times, with an increase of

70% between 1970 and 2004"

The report goes on to say there is 'very high confidence' that human activity has caused the planet to warm. This is primarily due to the burning of fossil fuels (56% of total GHG emissions in terms of CO2 equivalent) and agricultural activity which releases CO2 and CH4. Connected with this is land use change which is also a big contributor. The result is alarming; that concentrations of CO2 and CH4 in the atmosphere are far higher than any time over the last 650,000 years.

A pie chart illustrates the contribution of different sectors in total anthropogenic GHG emissions in 2004 (in terms of CO2 equivalent). The largest contributor is energy supply (25.9%), industrial activity is second largest (19.4%), forestry and deforestation is third (17.4%), agriculture is fourth with 13.5%, fifth is transport with 13.1%, sixth is residential and commercial buildings with 7.9% and last is waste and wastewater with 2.8%.

Interestingly, the report mentions that if only natural forcing is accounted for by itself, (i.e., volcanic eruptions, Earth's orbit around the sun, and solar output), over the last 50years the Earth would have actually cooled. Models prove this; "Observed patterns of warming and their changes are simulated only by models that include anthropogenic forcings".

This section ends by pointing out that in addition to causing a temperature increase, human activities have had other impacts on the climate system. These are listed below:

• very likely contributed to sea level rise during the latter half of the 20th century
• likely contributed to changes in wind patterns, affecting extra-tropical storm tracks and temperature patterns
• likely increased temperatures of extreme hot nights, cold nights and cold days
• more likely than not, increased risk of heat waves, areas affected by drought since the 1970s and frequency of heavy precipitation events.

To further support the anthropogenic nature of these changes, the paper reports that the physical and biological changes that are occurring are 'very unlikely' to be solely due to natural variability.

Chapter 1: Observed changes in climate and their effects

The first chapter outlines the observed changes in climate and their effects. The report begins with the bold statement that the climate is undeniably warming, citing the observed increases in atmospheric and ocean temperatures, widespread melting of snow and ice, and rising sea levels, as proof. These statements are exemplified by the fact that eleven of the last 12 years have been the hottest on record since 1850. It is likely that average Northern Hemisphere temperatures over the last 50 years have been hotter than any time over the last 1300 years. The report goes on to explain that the observed warming is global, though higher latitudes have warmed more than the lower latitudes, and land masses have warmed more than oceans.

The report says that there has been an average global temperature increase of 0.74 degrees Celsius over the last 100 years. Due to melting ice and thermal expansion, average sea levels have risen by 1.8mm/yr since 1961 and 3.1mm/yr since 1993, suggesting that sea levels are rising at an increasingly faster rate. In support of this, satellite images show that Arctic sea ice extent has deceased at an average rate of 2.7% per decade since 1978 and mountain glaciers are also retreating.

The warming atmosphere and oceans appear to be impacting rainfall patterns too, observed since 1900, indicted by increased rainfall in east North and South America, northern Europe and northern and central Asia. On the other hand, regions of the Sahel, the Mediterranean, southern Africa and southern Asia have experienced a reduction in rainfall (generally, increase in rainfall in higher latitudes, with a corresponding decrease in rainfall in sub tropical regions). The report concludes that globally there has likely been an increase in the occurrences of drought since the 1970s. It is likely that heat waves and heavy rainfall events have become more frequent, and there is evidence that the number of tropical cyclones has increased, and their storm tracks have increased pole ward. More evidence since the TAR supports this.




The report then moves on to highlight the impacts of increased temperature on various ecosystems. It is important to mention here that 29,000 data series from 75 studies have been assessed by the working group and most interestingly, 89% of the studys' conclusions are consistent with expected impacts of a warming planet. The IPCC has 'high confidence' warming has caused an increase in glacial lakes in snow and ice regions and increased ground instability in permafrost regions. There is 'high confidence' that rivers fed by glaciers and snow melt are experiencing earlier peak spring discharge. In terrestrial ecosystems, there is 'very high confidence' that spring is coming earlier and there has been a pole ward and upward shift in flora and fauna. In marine ecosystems, the increased temperature has affected ice cover, salinity and oxygen levels with a resulting impact on algal, plankton and fish abundance.

Impacts on human and natural environments have also been observed with 'medium confidence'. These include earlier spring planting of crops, increased mortality in the northern hemisphere due to heat waves, shifts in the patterns of infectious disease vectors, and a shrinking of snow cover on ski resorts.