Editor’s note: Centre Daily Times is observing Earth Day with a three-day series about climate change issues and how they affect Pennsylvania.
It’s one of the most polarizing issues in politics. But the science is all but certain: The climate is changing.
Climate is the average weather, said Richard Alley, Penn State Evan Pugh professor of geosciences and associate of the Earth and Environmental Systems Institute.
The climate changes if the sun changes its brightness, if the amount of sunlight that warms Earth changes or if the greenhouse effect changes, he said.
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During the course of Earth’s history, Alley said, “the evidence shows that natural changes in CO2 — and, to a lesser extent, in other greenhouse gases — have had the largest effect on climate. Those natural changes have generally been much smaller or slower than what we’re doing, though.”
The greenhouse gases in the atmosphere are important to human survival, but they can also be out of balance, said John Kelmelis, professor of international affairs at Penn State.
To determine atmospheric content throughout recent history, scientists are able to obtain ice cores and analyze the air trapped in bubbles. They use measurements of how far below the surface the air bubbles are located plus isotope analysis to calculate the age of the ice core, similar to determining the age of a tree from its rings and a piece of wood by carbon dating, said Kelmelis, who has coordinated the U.S. Geological Survey Global Change Research Program and directed the White House Scientific Assessment and Strategy Team.
During the past four interglacials — time between glacial periods — the highest carbon dioxide level was about 300 parts per million, Kelmelis said. Today, it’s 400 parts per million.
“One of the greenhouse gas constituents is way higher than normal, way higher than it’s been in the past 400,000 years. … What’s concerning scientists is there’s this big change in that blanket that holds heat in the Earth,” he added.
Carbon dioxide’s warming influence has been known for more than a century, Alley said.
According to Kelmelis, the past two years have been the warmest on record.
“The basic physics tell us that if one emits greenhouse gases, you expect the climate will warm,” said Klaus Keller, professor of geosciences at Penn State.
One of the first people to recognize that humans can change the climate was Swedish chemist Svante Arrhenius, Keller said.
He made a calculation that if people emit carbon dioxide, the climate would warm. It was a hypothesis then, but in the past few decades it has become clear that humans are responsible, Keller said.
“The major cause of climate change … in this century is … humans. It’s us,” Keller said.
But, there’s never absolute certainty, Keller added.
Climate change and living things
“The history of climate shows very clearly that when climate has changed, living things have been affected greatly — migrating or being driven to extinction,” Alley said.
The effects of climate change are already visible.
Maps of temperatures show an overall warming pattern, glaciers are receding, sea ice is receding and getting smaller and thinner, ice caps are changing, heat waves are becoming more intense, Keller said.
Other issues that will arise with climate change include rising sea level, expanding droughts and fewer freezes that kill disease-carrying insects, Alley said.
“Most of the Earth,” Alley said, “and most of the people are in places that recent analyses indicate will be hurt economically.”
But economics aren’t the only concern. Health is a major factor.
A recent report — “The Impacts of Climate Change on Human Health in the United States: A Scientific Assessment” — released by the White House indicates that climate change is a significant threat to health.
The report, developed over three years by about 100 experts in climate change science and public health, describes a variety of risks — not only worsening existing health threats but also creating new ones.
Among the findings were that climate change will likely contribute to exacerbating allergy and asthma conditions; increasing the likelihood of exposure of food to pathogens and toxins; severe heat is expected to cause more premature deaths; and the most vulnerable — children, the elderly and the poor — will be the most affected in society.
But despite the seemingly dire predictions, things are being done.
The United States has reduced its carbon dioxide production, Kelmelis said.
“We’ve got a lot of laws that have gone into place that have either encouraged or required actions that have reduced the U.S.’s emission of greenhouse gases into the atmosphere,” he said.
“The best scholarship is clear, that if we use the science, together with what we believe in and where we want to go, we get a bigger economy with more jobs, greater national security in a cleaner environment. … Large efforts will be required over decades to do this, but they can pay very large dividends in many ways,” Alley said.
Clean Power Plan and the commonwealth
In August, President Barack Obama and the U.S. Environmental Protection Agency announced the Clean Power Plan — an effort to reduce carbon pollution from power plants.
The hope – once the Clean Power Plan is fully in place in 2030 – is that carbon pollution from power plants will be 32 percent lower than 2005 levels, according to the EPA.
The Clean Power Plan allows states to develop either an emission standards plan or a state measures plan and allows flexibility for how states meet the carbon pollution standard, according to the EPA.
In February, the U.S. Supreme Court halted implementation of the plan pending a judicial review after 29 states and numerous industry groups challenged the plan.
The challenge argues that, through the Clean Power Plan, the EPA attempts to reorganize nearly every state’s energy grid and therefore is in violation of the Clean Air Act.
The challenge is before the U.S. Court of Appeals for the District of Columbia Circuit, and oral arguments will be heard on June 2.
John Quigley, secretary of the Pennsylvania Department of Environmental Protection, said the commonwealth is still doing the planning work but will not submit a plan while the stay is pending.
He added that since 2007, carbon dioxide emissions have fallen by 20 percent in Pennsylvania. The state is on its way to meeting the goals of the Clean Power Plan, but a concerted effort and focus on energy efficiency and renewable energy will still be necessary.
“I think we should go through with (the Clean Power Plan). ... I think our industry is smart enough to figure out how to do that. Because the plan doesn’t tell them how to do it, it just tells them what needs to be the outcome. And we’ve got a very creative and capable industry in the United States. ... If we get in on the front end of this, I think that we will be building new industries rather than destroying old industries,” Kelmelis said.
Sarah Rafacz: 814-231-4619; @sarahrafacz