President Donald Trump declared that the United States will be withdrawing from the Paris climate accord June 1. The agreement aims to reduce greenhouse gas emissions from countries across the world. It currently includes 195 nations.Professor William Shobe, Director of the Center for Economic and Policy Studies, said the Paris climate accord is an improvement on the Kyoto Protocol. The Kyoto Protocol differed from the Paris Accord in the structure of responsibilities of the member nations. “One of the key differences between the Paris Accord and the Kyoto Protocol and earlier efforts is that [the former] was designed in such a way that every country offered up a voluntary contribution to the overall effort rather than the nature of the Kyoto Protocol — which was the top down allocation of responsibilities from the central treaty language,” Shobe said. According to Shobe, the voluntary nature of the treaty encouraged more participation and made the Paris Accord more successful than the preceding Kyoto Protocol.Environmental Sciences Prof. Howard Epstein said in an email statement the goal of the Paris Accord is to prevent an increase in global temperatures by more than two degrees Celsius. According to Epstein, the temperature has increased by about one degree Celsius over the past century. However, the change in temperature has not been uniform across the globe, said Epstein.“There are some areas that have actually cooled over that same time period — although the area warming is much more extensive than the area that has cooled — and the Arctic for example is warming at least twice as fast as the rest of planet,” Epstein said. According to Kevin Grise, Assistant Professor from the Department of Environmental Sciences, this overall increase in global temperatures can be attributed to the increase in greenhouse gases such as carbon dioxide, methane and nitrous oxide. “Increases in these gases due to human activities are responsible for amplifying the natural greenhouse effect of the planet, causing the planet's temperature to increase,” Grise said in an email statement.This elevation in temperature has had many visible effects on the environment from the melting of ice in the Arctic to changes in vegetation. According to Grise, ice is melting at an unprecedented rate in the Arctic.Epstein said there are diverse effects of such melting. For one, the melting of ice displaces many animals, like the polar bears and walruses for which the ice serves as a home. Furthermore, the thawing of permafrost causes the release of more greenhouse gases such as carbon dioxide and methane into the atmosphere, further contributing to the increases in temperature. This increase in thawing has also led to a rise in sea levels, which has the potential to affect populations living along coastlines.The effects of the increasing temperature are not limited to solely the Arctic or the melting of ice. Hank Shugart, W.W. Corcoran Professor of Natural History, conducted a study examining the effects of an increase in temperatures by three degrees Celsius on biodiversity reserves in Africa. The study found that this rise in temperature resulted in a change of habitat for more than half the animals in these parks.According to Grise, evidence of climate change cannot be attributed to a single incident.“People want to use individual weather events to claim that climate change is or is not happening,” Grise said. “Climate change is not proved by one big storm, drought or heat wave ... climate change is realizing that the nights are warmer now on average than they were 30 years ago.”The main way for the world to combat the globally rising temperatures is to implement policies aimed at minimizing greenhouse gas emissions. The Paris climate accord set out to fulfill this mission by allowing countries to set voluntary goals for themselves.While Shugart believes the treaty is weak as it is non-binding and disadvantages developing nations, he said that it is better than taking no action.“If you can think having a bad treaty is a bad thing, think about having no treaty — and that's kind of where we're headed,” Shugart said. “The policy part is going in a very scary direction right now at a global level.”According to Shobe, the withdrawal of the United States from the agreement has several policy and economic implications. For instance, leaving the treaty appears to be a shift in global leadership in environmental policy.“With the U.S. abdicating its leadership role, there's an opportunity for other countries to step up and take that mantle — like China and the European Union, for example,” Shobe said. “So there may be a perceived benefit in those countries to maintaining [a] connection with the international effort to reduce CO2 emissions and in fact picking up where the U.S. has failed.”Trade between the United States and other nations may also be impacted by withdrawal from the treaty. Since industries in the U.S. are not liable for limiting their carbon dioxide emissions, produced goods may be subject to additional taxes by other nations as a penalty. Therefore, industries will most likely implement plans to reduce emissions due to the market trends.The renewable energy industry should not be affected by this shift in environmental policy, at least in the short run, according to Shobe.“There is no mandate for renewables in Virginia but we're seeing a rapid expanse in renewables in the states because customers are demanding it,” Shobe said. “U.Va. itself has invested in a couple of solar farms to be built to serve our own electricity needs. So customers all around the Commonwealth are demanding access to renewable energy — this has nothing to do with the Paris climate accord.”However, Shobe foresees a decrease in innovation and businesses in the renewable energy sector in the long run which will be damaging to the economy and competitiveness of the U.S. markets.“It would be one of the unsung costs of leaving the Paris Accord is the idea that we're just not a great place to do wind and solar innovation anymore — that should be done in Europe or China or India rather than the U.S.,” Shobe said.Ultimately, the high levels of greenhouse gases will remain for at least the next century according to Epstein. “The question is how high will these concentrations get and how long before we actually get close to removing greenhouse gases from the atmosphere rather than putting them there,” Epstein said.Despite the withdrawal from the treaty, the United States will most likely continue to move towards reductions in greenhouse gas emissions on a state and local level. In fact, the United States Climate Alliance has already formed in response to Trump’s withdrawal from the treaty.This alliance currently consists of thirteen states — including Virginia — that want to work to reduce greenhouse gas emissions. Shobe said that the impact of the alliance on the environment remains to be seen as it is still too early. For now, it can be viewed as a group of states expressing interest in an issue. However, the lack of federal support increases the costs of implementing these policies and prevents localities from taking more aggressive measures to reduce emissions.The effects of withdrawal from the Paris Climate Accord have yet to be seen in terms of greenhouse gas emissions and global temperature change. But according to Shugart, even an increase in two degrees — as outlined by the agreement — can have profound effects.“If it's two degrees warmer tomorrow then it's not a big deal, but if it's two degrees warmer every tomorrow forever then it is a big deal,” Shugart said.