Why is 217 the hottest year in history?
The most important factor of temperature rise is human activities, and secondly, the appearance of La Nina phenomenon in 217 also led to the gradual increase of temperature.
So, there are two main reasons for making 217 the hottest year in history:
Long-term impact of human activities
La Nina phenomenon
According to the British "Daily Mail" reported on January 18th, a new study found that 217 became the hottest year in history without El Niñ o phenomenon.
In the year of El Niñ o, the prevailing wind direction will change, which will lead to the increase of water temperature in a large area of the Pacific Ocean, thus leading to the increase of global temperature.
compared with the year of El Nino, the temperature in 216 has increased, but 217 has the largest increase and has become the hottest year in history.
scientists say that in the past 15 years, the most important factor of temperature rise is human activities.
This includes the burning of fossil fuels, which releases a lot of heat-absorbing greenhouse gases into the atmosphere.
scientists say that human-induced climate change is beyond the power of nature itself.
according to the temperature records in 217, world leaders should focus on the scale and urgency of the risks caused by climate change.
Experts from the Hadley Center of the British National Weather Service and the Climate Research Center of the University of East Anglia participated in this research, and made a "Hadcrut4" data set to assess global temperature.
The results show that the temperature level in 217 is 1℃ (1.8 F) higher than the pre-industrial level from 185 to 19, and .38 C (.78 F) higher than the average level from 1981 to 21.
217 became the hottest year in history.
A series of international analysis data from the National Oceanic and Atmospheric Administration (NOAA) and the National Aeronautics and Space Administration (Nasa) also show that 217 has become the hottest year in history.
The temperature in 217 exceeded the highest temperature recorded in 216, and some data were higher than those analyzed in 215.
In 215 and 216, El Niñ o occurred, which is a natural phenomenon in the Pacific Ocean. Besides man-made global warming, El Niñ o will also increase the temperature.
Dr. Colin Morice of the Hadley Center of the British National Weather Service said that the global temperature data measured by the center in 217 were consistent with those measured by other centers in the world. Without the influence of El Niñ o, 217 became the hottest year in three years and the hottest year since 185.
215, 216 and 217 have become the three hottest years.
in addition to persistent greenhouse gas emissions, 215 and 216 were also affected by the strong El Niñ o phenomenon.
However, 217 is the most noteworthy year, because the El Niñ o phenomenon did not appear in that year, but the La Niñ a phenomenon occurred, but the temperature continued to rise.
the persistent El Nino phenomenon in 215-216 increased the annual average temperature in 216 by about .2 c (.36 f), which was about 1.1 c (2 f) higher than the average temperature in 185-19.
according to the annual global average temperature forecast of the British Meteorological Office in 217, the global average temperature in 217 is expected to exceed the long-term average level and remain between .32 C (.57 F) and .56 C (1 F).
according to the average of the three major temperature data sets in the world, the temporary data in 217 is .42 c (.75 f) higher than the long-term average, which is within the forecast range.
The forecast at the end of 216 correctly analyzed that 217 will be one of the hottest years in history.
"hadcrut4" global temperature data set is compiled from thousands of global temperature measurement data.
the regional variation of temperature itself provides reference information for understanding the causes of warming mechanism, so as to cope with the persistent accumulation of greenhouse gases in the atmosphere.
Professor Tim Osborne, research director of the Climate Research Department of the University of East Anglia, added that it is necessary not only to analyze the global average temperature data, but also to explain the geographical pattern of climate warming.
At first, the understanding of climate physics was that the greater the warming extent in the land and the Arctic region, the smaller the warming extent in the sub-polar region. Now, this result has been observed.
The World Meteorological Organization (WMO) has compiled five major international data sets and said that the temperature has been rising for a long time.
Petteri Taalas, Secretary General of the World Meteorological Organization, said that the long-term temperature change trend is more important than the ranking of individual years, and this trend will increase.
of the 18 hottest years recorded, 17 occurred in this century, but the degree of warming in the past three years was an exception.
The warming change in the Arctic is particularly significant, which will have a far-reaching impact on sea level and weather conditions in other parts of the world.
It also said that the temperature rise in 217 directly caused many countries around the world to be affected by extreme weather.
The United States has experienced the worst year affected by extreme weather and climate disasters, while other countries have also experienced economic slowdown or reverse growth due to tropical cyclones, floods and droughts.
President Trump has announced that the United States plans to withdraw from the Paris Agreement, the world's first comprehensive agreement on reducing greenhouse gas emissions, which will make the United States the only country that has not signed the agreement.
Bob Ward, an expert on climate change at the London School of Economics and Political Science, said that although he did not participate in this research, with the increase of temperature, extreme weather will occur one after another around the world, such as hurricanes in the Caribbean and the United States.
all countries will face the impact of climate change.
this year, * * * will begin to assess the gap between reducing greenhouse gas emissions and the targets of the Paris agreement.
according to the recorded temperature data, world leaders should focus on the magnitude and urgency of global climate change risks caused by population, wealth and climate change.
because the observation data can't cover all parts of the world, especially in polar regions, and the measuring equipment used to generate data sets also has limitations, the calculation results are full of uncertainties.
The existing data of various assessment differences mainly come from sporadic data in polar regions.