Global Climate Change
Climate change refers to changes in the climate on Earth that have been discovered since the 1900s. The changes we have seen recently and are expected to take place over the next 80 years are largely due to human behavior rather than natural changes.
Thaba-Tseka village in Lesotho. Crops in the rugged mountains of Lesotho continue to decline as rain falls either too early or too late. And big hail and tornadoes. The premature frost killed most of the corn seedlings that had survived the strange weather in the previous period.
The old people in the village believed that the universe was in chaos. They said, "God must be angry with us, but I don't know why."
This village and nearly four million other Africans, who are at risk of starvation, may be among the first victims of global climate change... …
In the past 50 years, the minimum temperature in northern China has increased significantly, and warm winter years have appeared consecutively.
Question: Why is the climate warming?
Greenhouse Gases Greenhouse Gases
Keep the Earth
Warm The Earth would be 30 degrees cooler than it is today without greenhouse gases
99% of the atmosphere is made up of 78% nitrogen and 21% oxygen. They have little direct effect on climate regulation.
Question: What are the greenhouse gases?
There is a small fraction in the remaining 1% or so of the atmosphere: Carbon dioxide,
Carbon dioxide
, Methane, Methane
, Nitrous oxide,
Ozone, Ozone
, Water vapor, Water vapour
The Halocarbons
Question: What Causes Greenhouse Gas Increases?
Burning coal, oil and natural gas produces carbon dioxide
Deforestation reduces the carbon dioxide absorption capacity of vegetation
Greenhouse gas conditions
CO2 concentrations are now approximately 30-35% higher than natural conditions
Methane, 25% nitrous oxide
Commercial energy consumption comes from
transportation Intergovernmental The Intergovernmental Panel on Climate Change (IPCC) (1988),
its third assessment report estimated that by the end of the century, the global temperature will increase by 1.4C~5.8C.
In 2001, the warming observed in the last 50 years is very likely "most of the warming observed over the last 50 years is likely to be attributable to human activities" due to human activities.
In 1996, "discernible human influence on the climate"
on global climate change Key point:
Global temperature has risen by more than 0.7°C over the past 300 years, so climate change has already occurred. Temperatures increased by 0.5°C in the 20th century. The most severe warming occurred between 1910-1940 and from 1976 to the present.
The 1990s were the warmest in the last 1,000 years, and 4 of the 5 warmest years occurred in the 1990s. 1998 was the warmest year globally since records began in 1861. 1995 was the year with the most hot days in 225 years, with 26 days above 20°C. The number of cold days (average temperature below 0°C) has decreased from 15-20 days per year before the 20th century to about 10 days per year in recent years.
Snow cover in the Northern Hemisphere has decreased by about 10 percent since 1960, mountain glaciers have retreated significantly during the 20th century, and snow and ice thickness in the Arctic has lost nearly 40 percent over the past 40 years.
Climate change has caused global sea levels to rise by an average of 0.1 to 0.2 meters over the past 100 years. In the 20th century, the average annual increase was 1 to 2 mm. It is estimated that from 1999 to 2100, the increase was 0.09 to 0.88 meters, which was 2 to 4 times higher than that in the 20th century.
Rainfall has increased markedly in most parts of the world, with an increase of 0.5% to 1% every 10 years in the middle and high elevations of the northern hemisphere, and a 2% to 4% increase in the incidence of severe rainfall events. The frequency and severity of droughts in Asia and Africa have been increasing over the past few decades.
The second half of the 21st century will see increased winter rainfall in mid-to-high northern latitudes and Antarctica. Meanwhile, Australia, New Zealand and South Pacific islands, Central America, and southern Africa are likely to experience reduced winter rainfall.
There are already signs that biodiversity is starting to respond to global climate change.
Heat-related illness and death are also more likely. Infectious diseases carried by insects and rodents can spread more widely to areas where they were not previously present.
If the global climate change trend continues unabated, global warming will threaten our human health. Threats cities, farms, forests, beaches and wetlands, and other natural habitats.
Biodiversity responses to global climate change include changes in
geographic distribution, changes in
physiology, changes in
life cycles, and changes in
migration habits and habitats
Reduced viability Changes in
biology
Early spawning of frogs, northward expansion of
butterfly ,
faster egg hatching in UK, early flowering of trees in
eastern Europe ,
some biodiversity-rich areas already affected Birds in
Costa Rica
Mosquitoes in Tanzania and Indonesia
plus Butterfly in
Livonia Frost-intolerant plants rise to new altitudes
Edith's Checkerspot Butterfly distribution shifts
California north to Canada, south to Mexico
Extinct in its southern range, north and north Expansion of high-altitude areas
Mosquitoes appear at higher altitudes
Distribution shifts with disease transfer
Transfers to higher-altitude areas, where Malaria or other mosquito-borne diseases have never been seen before, also began to occur
in Tanzania and Indonesia in 1997 The first malaria outbreak in the tropical highlands.
Dengue fever, previously only found below 1000 meters, is now reported in Mexico at nearly 2000 meters. The vector insects of dengue and yellow fever (Yellow Fever) have been found over 2000 meters in Colombia.
Resplendent quetzals distribution shift Monte Verde forest,
Costa Rica , where climate change has led to increased nesting sites
of the toucans Predation on the young of Resplendent quetzals (
Pharomachrus No higher altitudes Districts can nest
Reduce snow and ice cover
Increase the melting of polar ice caps
Increase land and ocean
water sea
water From 1999 to 2100, the increase was 0.09 to 0.88m, and the median value was 0.48m, which was 2-4 times higher than that in the 20th century. Effects of sea level rise Coastal flooding Land collapse Estuarine deltas Human activities Wildlife habitats Already below sea level (Ireland) Small island states Habitat Loss and Fragmentation Habitat Loss and Fragmentation Resource development, town development, transportation networks, navigation facilities and other forms of habitat change that start at the edges first Degradation of remaining vegetation Traffic roads lead to easier access to previously isolated forests
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