Basic Observation of Climate Change in IPCC 5th Report
IPCC(Intergovernmental Panel of Climate Change) is the largest scientific body founded by United Nation. It assesses all sort of data related to climate change. And then it publishes assessment report. In Nov, 2014 the 5th assessment report was published. Because 5th assessment report contains enormous amount of data, synthesis report published in 2015. I will summarized ‘observation’ of climate change in synthesis report. I would not cover ‘prediction’ of climate change in this writing. (Italic is directly qoute from report)
The globally averaged combined land and ocean surface temperature data as calculated by a linear trend show a warming of 0.85 [0.65 to 1.06] °C. Each of the last three decades has been successively warmer at the Earth’s surface than any preceding decade since 1850.
The temperature of world is not stable. There is temperature change cycle in the Earth. Figure 1 shows climate change cycle in the Earth. There is Up and Down cycle every 100,000 years. C02 and Temperature has a correlation. In this cycle, after bottom of temperature, there is dramatic ‘increase season’ of temperature(about 12°C) in 10,000 years; 1.2 °C in crease in every 1,000 year. At this point, Co2 level is about 280 ppm.
We do not know when is the exact peak of Temperature rise. However, increase in 1850–2010 is 1 °C increase in 1o0 years. The speed is too fast.
Figure 2 is temperature change from AD 500–2000. Global temperature does not change much between 500–1800. This means temperature already reached the peak, and this is not dramatic ‘increase season’. And there is a sudden dramatic increase after 1850. Temperature between 1850–2010 is definitely ‘unnatural’.
Sea Level Rise
Over the period 1901 to 2010, global mean sea level rose by 0.19 [0.17 to 0.21] m . The rate of sea level rise since the mid-19th century has been larger than the mean rate during the previous two millennia.
90% of Energy added by global warming absorbed by ocean. The ocean is getting warmer. According to IPCC, the global average warming trend has been 0.11 [0.09 to 0.13]°C per decade over this time. The temperature change in ocean can cause a ocean circulation change; salinity , precipitation, evaporation.
Greenhouse Gas Emission
Anthropogenic greenhouse gas emissions have increased since the preindustrial era, driven largely by economic and population growth, and are now higher than ever. This has led to atmo-spheric concentrations of carbon dioxide, methane and nitrous oxide that are unprecedented in at least the last 800,000 years. Their effects, together with those of other anthropogenic drivers, have been detected throughout the climate system and are extremely likely to have been the dominant cause of the observed warming since the mid-20th century.
There is a natural cycle of temperature and Co2. The maximum C02 is 280 ppm. In 2010, the Co2 concentration is about 380 ppm. There is no such period which Co2 level is 380 ppm. This is extreme level of Co2 level. Greenhouse gas captures thermal energy; this means there is possibility of potential temperature rise. This is unusual amount of CO2 level.
The statistical model of climate change is not perfect. However, there is credible evidence the world is warming. Intuitively, it is not natural speed of temperature change.
Climate change is not an illusion.