Most climate scientists agree the main cause of the current global warming trend is human expansion of the “greenhouse effect”— warming those results when the atmosphere traps heat radiating from Earth toward space. Long-lived gases that remain semi-permanently in the atmosphere and do not respond physically or chemically to changes in temperature are described as “forcing” climate change. Gases, such as water vapor, which respond physically or chemically to changes in temperature are seen as “feedbacks.” The consequences of changing the natural atmospheric greenhouse are difficult to predict, but certain effects seem likely. On average, Earth will become warmer. Some regions may welcome warmer temperatures, but others may not. Warmer conditions will probably lead to more evaporation and precipitation overall, but individual regions will vary, some becoming wetter and others dryer. A stronger greenhouse effect will warm the oceans and partially melt glaciers and other ice, increasing sea level. Ocean water also will expand if it warms, contributing further to sea level rise. Meanwhile, some crops and other plants may respond favorably to increased atmospheric CO2, growing more vigorously and using water more efficiently. At the same time, higher temperatures and shifting climate patterns may change the areas where crops grow best and affect the makeup of natural plant communities.
The industrial activities that our modern civilization depends upon have raised atmospheric carbon dioxide levels from 280 parts per million to 400 parts per million in the last 150 years. The panel also concluded there’s a better than 90 percent probability that human-produced greenhouse gases such as carbon dioxide, methane and nitrous oxide have caused much of the observed increase in Earth’s temperatures over the past 50 years. The rate of increase in global warming due to these gases is very likely to be unprecedented within the past 10,000 years or more.The other major planetary transformation arising from direct and indirect effects of greenhouse gases is the rise of ocean levels and their acidity. Between 443 billion and 629 billion tons of meltwater are added to the world’s oceans each year, which raises sea level by about 1.5 millimeters a year. This is in addition to the 2-millimeter yearly rise caused by expansion of the warming ocean.
Current efforts by many governments to stem this kind of climate change are not going to be enough. Even if we implement existing agreed-upon standards, we would still not secure the planet’s sustainability. Consider two future patterns: one under current conditions and the second if we implemented all current agreements to reduce environmental damage. It would make a difference, but one far too small to alter the basic trajectory. Existing agreements to address environmental destruction operate at a level and through formats that fail to address the deeper dynamics causing the climate change. These dynamics cut across the existing boundaries and divisions of the interstate system.