The latest report from the IPCC describes the effects of climate change more specifically and forcibly than any other IPCC report. Yet The IPCC process is inherently conservative and many scientists believe that the report is understating the severity of climate change and some of the biggest risks.
Even though the synthesis report is more alarming than its predecessors, some researchers believe that it still understates the trajectory of global warming and its impact. The I.P.C.C.’s scientific process, which takes five years of study and writing from start to finish, cannot take into account the very latest data on climate change or economic trends, which show larger than predicted development and energy use in China.
“The world is already at or above the worst case scenarios in terms of emissions,” said Gernot Klepper, of the Kiel Institute for World Economy in Kiel, Germany. “In terms of emissions, we are moving past the most pessimistic estimates of the I.P.C.C., and by some estimates we are above that red line.”
Governments around the world have long promised action, it is time for policymakers to fullfill those promises. We have waited long enough.
Here are the key findings of the report:
- “Warming of the climate system is unequivocal, as is now evident from observations of increases in global average air and ocean temperatures, widespread melting of snow and ice, and rising global average sea level.”
CAUSES OF CHANGE
- “Most of the observed increase in globally averaged temperatures since the mid-20th century is very likely due to the observed increase in … greenhouse gas concentrations” from human activities.
- Global total annual greenhouse gas emissions from human activities have risen by 70 percent since 1970. Concentrations of carbon dioxide, the main greenhouse gas, far exceed the natural range over the last 650,000 years.
PROJECTED CLIMATE CHANGES
- Temperatures are likely to rise by between 1.1 and 6.4 Celsius (2.0 and 11.5 Fahrenheit) and sea levels by between 18 cms and 59 cms (seven and 23 inches) this century.
- Africa, the Arctic, small islands and Asian mega-deltas are likely to be especially affected by climate change. Sea level rise “would continue for centuries” because of the momentum of warming even if greenhouse gas levels are stabilised.
- “Warming could lead to some impacts that are abrupt or irreversible”. About 20-30 percent of species will be at increasing risk of extinction if future temperature rises exceed 1.5 to 2.5 Celsius.
REASONS FOR CONCERN
- Risks to unique and threatened systems, such as polar or high mountain ecosystems, coral reefs and small islands.
- Risks of extreme weather events, such as floods, droughts and heatwaves.
- Distribution of impacts — the poor and the elderly are likely to be hit hardest, and countries near the equator, mostly the poor in Africa and Asia, generally face greater risks such as of desertification or floods.
- Overall impacts — there is evidence since 2001 that any benefits of warming would be at lower temperatures than previously forecast and that damages from larger temperature rises would be bigger.
- Risks or “large-scale singularities”, such as rising sea levels over centuries; contributions to sea level rise from Antarctica and Greenland could be larger than projected by ice sheet models.
- Climate change is expected to magnify regional differences in Europe’s natural resources and assets. Negative impacts will include increased risk of inland flash floods, and more frequent coastal flooding and increased erosion (due to storminess and sea-level rise).
- Mountainous areas will face glacier retreat, reduced snow cover and winter tourism, and extensive species losses (in ome areas up to 60% under high emissions scenarios by 2080).
- By 2020, between 75 and 250 million of people are projected to be exposed to increased water stress due to climate change.
- By 2020, in some countries, yields from rain-fed agriculture could be reduced by up to 50%. Agricultural production, including access to food, in many African countries is projected to be severely compromised. This would further adversely affect food security and exacerbate malnutrition.
Australia and New Zealand
- By 2030, water security problems are projected to intensify in southern and eastern Australia and, in New Zealand, in Northland and some eastern regions.
- By 2020, significant loss of biodiversity is projected to occur in some ecologically rich sites including the Great Barrier Reef and Queensland Wet Tropics.
- Endemic morbidity and mortality due to diarrhoeal disease primarily associated with floods and droughts are expected to rise in East, South and South-East Asia due to projected changes in the hydrological cycle.
- By the 2050s, freshwater availability in Central, South, East and South-East Asia, particularly in large river basins, is projected to decrease.
- During the course of this century, cities that currently experience heatwaves are expected to be further challenged by n increased number, intensity and duration of heatwaves during the course of the century, with potential for adverse health impacts.
- Warming in western mountains is projected to cause decreased snowpack, more winter flooding, and reduced summer flows, exacerbating competition for over-allocated water resources.
- There is a risk of significant biodiversity loss through species extinction in many areas of tropical Latin America.
- Changes in precipitation patterns and the disappearance of glaciers are projected to significantly affect water availability for human consumption, agriculture and energy generation
- Sea-level rise is expected to exacerbate inundation, storm surge, erosion and other coastal hazards, thus threatening vital infrastructure, settlements and facilities that support the livelihood of island communities.
- Governments have a wide range of tools — higher taxes on emissions, regulations, tradeable permits and research. An effective carbon price could help cuts.
- Emissions of greenhouse gases would have to peak by 2015 to limit global temperature rises to 2.0 to 2.4 Celsius over pre-industrial times, the strictest goal assessed. The costs of fighting warming will range from less than 0.12 percent of global gross domestic product (GDP) per year for the most stringent scenarios until 2030 to less than 0.06 percent for a less tough goal. In the most costly case, that means a loss of GDP by 2030 of less than 3 percent.