# Planet Earth/4l. Earth’s Climate and How it Has Changed
## Weather versus Climate

Simply put, the difference between weather and climate is time. Weather is what conditions exist in the Earth’s atmosphere over a short period, while climate is how the atmospheric conditions change over long periods of time. In science, climate is the average patterns of weather over long multi-year studies. Since the Earth’s weather patterns oscillate daily, seasonally, and over decades, climate is important because it allows you to see the overall trends that can impact future decisions.

## NASA and the discovery of global warming

In 1967, a young researcher named James Hansen arrived in New York City. A bright student of mathematics and physics, Hansen had accelerated through his studies at the University of Iowa, and spent a year at the University of Tokyo, where he continued his interest and study of the carbon dioxide rich atmosphere of Venus. It must have been an exciting time in history to be interested in astronomy, as NASA tested out its new Saturn V rockets to send humans to the moon. Hansen was employed by a new division of the Goddard Space Flight Center, the branch of NASA dedicated to getting the United States into space. Named after the American Rocket Scientist Robert Goddard, the Goddard Space Flight Center was located near Washington D.C., and a new organization was created as a partnership with Columbia University in New York City to facilitate the academic study of the new scientific data arising out of the exploration of space by NASA. The Goddard Institute for Space Studies, sits on the corner of 112th and Broadway in Manhattan in the same building as Tom’s Restaurant that appeared in the popular 1990s television show Seinfeld, and spawned the hit song by Suzanne Vega. In essence, not the typical location for a government sponsored program to study space science. Nevertheless, the ideal collaboration with university students from the University of Columbia and visiting scientists from Washington D.C. led to an innovative center to study the enormous amounts of information that was being collected from outer space, with the launch of more specialized and sophisticated satellites and missions into space. James Hansen was at home at the small institute, and continued to study the atmosphere of Venus from his office above the bustling city streets below. In 1981, he rose up to become the director of the Goddard Institute for Space Studies, as his attention turned to the study of the Earth and its atmosphere.
James Hansen, and his team of atmospheric physicists published one of the most prophetic scientific papers in the journal Science in 1981: Climate impact of increasing atmospheric carbon dioxide. In the paper, the authors examined the historical records of temperatures recorded since the 1880s and found that the Earth’s overall global temperature had increased through the century with a warming of 0.4°C from 1880 to 1980. The team made several important predictions regarding the climatic effect of rising carbon dioxide. They predicted that from 1980 to 2080, global temperatures would rise approximately 2.5°C, with a warming of 0.6°C by the year 2000, and reach a 1.0°C increase by the year 2030. The study was visionary because it offered a prediction that could be tested. In 2000, twenty years after the paper was written, the record of global temperatures showed a 0.4°C warming from the baseline (from 1951–1980), and by 2020 was higher than the warming predicted in the 1981 paper, between 0.8 to 0.9°C, well on the way to reaching 1°C global warming before the year 2030, even faster than predicted in the 1981 paper.
The paper was met with some skepticism from scientists and was largely under the radar for most news media at the time. Today the paper’s well-known predictions are highly regarded by the entire scientific community, on par to Albert Einstein’s astronomic predictions a century ago. Things changed for James Hansen in 1988, when he was asked to speak in front of a meeting of the Senate Committee on Energy and Natural Resources. These select Senators set federal policy regarding the extraction of fossil fuels from lands owned by the U.S. government, as well as set policies regarding energy regulations for citizens, such as establishing energy standards for the efficiency of automobiles. Hansen’s speech that he gave to the politicians was widely reported on by the newspapers of the time, and his graph of increasing global temperatures landed on the front page of the New York Times. The risk of climate change and the danger it posed to Earth led the United Nations to create that same year the Intergovernmental Panel on Climate Change (IPCC) in 1988, an international group of experts to review Earth’s changing climate and issue comprehensive reports on the observed changes to the Earth’s global temperatures, as well as report on various governmental responses to address climate change.
In the forty years since James Hansen’s team from the Goddard Institute for Space Studies reported on rising global temperatures, significant investment has been made to track global warming, both from weather stations as well as increasingly sophisticated monitoring of sea and land surface temperatures from satellites. Currently 18 of the last 19 years have been the warmest global temperatures on record, with a dramatic rise in global temperatures in those forty years since 1981. Warming climates have resulted in abrupt changes to sea level with coastal flooding, loss of sea ice, disappearance of glaciers, droughts, and the rising risk of forest fires. Fatalities from climate induced deaths (fires, cyclones, heat-waves), as well as rising carbon dioxide and other air pollutants has risen dramatically since 1981. Public opinion demonstrates a growing fear of the real danger of climate change from 25% of Americans seriously worried in 1998 to 41% in 2016. There is also a major age gap, with older Americans over the age of 55 being the least concerned about risks of climate change, while those between 18 and 34 are the most concerned..
The United Nations formed in 1945, in the aftermath of World War II, as an intergovernmental organization with a mandate to maintain international peace and security, foster friendly relationships between nations, and aid international cooperation between nations on Earth. Since its formation, the United Nations has struggled with its mission due to the fractured authoritarian nature of individual countries and their respective leadership. While the United Nations has failed to end wars on the planet, it has done well in keeping peace between nations in times of conflict and civil war. With the added goal in 1988, with the formation of the Intergovernmental Panel on Climate Change, the United Nations had taken on a new role to attempt to solve the carbon dioxide crisis, by working with governments to pass laws and regulations to curb or end emissions of carbon dioxide into the atmosphere. In 1992 the United Nations Framework Convention on Climate Change (UNFCCC) was established, and in 1997 the Kyoto Protocol was signed as an international agreement to reduce carbon dioxide emissions. However, the Kyoto Protocol was never signed by the United States of America, and while most nations agreed to reductions, the lack of support from the United States led to a growing lack of global support, and then Canada withdrew from the agreement in 2012. Meanwhile, Japan, New Zealand and Russia did not propose new commitments in the second round of the agreement which spanned until 2020. The 2016 Paris Agreement was aimed to strengthen the global response to climate change by keeping global temperature rise below 2 degrees Celsius above pre-industrial levels. While grand in its goals, the Paris Agreement was considered ineffectual, and likely to fail given the rapid rise in global temperatures already underway. The major industrialized nations, which emit the most carbon dioxide into the atmosphere, failed to implement policies to meet pledged carbon dioxide emission targets and the carbon dioxide concentration in the atmosphere showed an increased growth rate in 2015, 2016, and 2018 to around 3.0 ppm per year as recorded at the Mauna Loa Observatory in Hawaii. In 2017, with the election of Donald Trump as the 45th President of the United States, the US notified the UN of its intention to withdraw from the agreement. The failure to meet any of these pledges since 1988 has resulted in an average 17% rise in carbon dioxide in the air you breath since 1988 (351 ppm to 410 ppm). In 2015 a reporter interviewed a much older and wiser James Hansen, now retired from NASA, but still strongly vocal on the need to curb carbon dioxide emissions. “It’s all embarrassing really, after a while you realize as a scientist that politicians don’t act rationally.” Indeed, his comments hold very true, as policy makers have demonstrated an inability to make significant reductions in the total emissions of carbon dioxide into Earth’s atmosphere.
Politicians could significantly reduce carbon dioxide emissions by carrying out three simple actions, first eliminate the sale of government-controlled fossil resources within their country, second impose fees to companies that emit carbon dioxide into the atmosphere, and three outlaw hydrocarbon energy generation for electricity, replacing electrical generation with nuclear, hydroelectric dams, solar, and wind farms. However, politicians derive much economic incentive, such as campaign contributions, with the sale and distribution of hydrocarbon fuels, and have kept a status quo in the continued use of these atmospheric pollutants in order to remain in power.

## How hot will Earth get?

The study of climate change is complex due to the nature of averaging large sets of weather data over numerous years of data collection. Owing to the growing number of weather stations over time, the record of daily high and low temperatures has grown exponentially as humans have recorded a great amount of the temperature fluctuation of the Earth’s surface. In 2010, Berkeley Earth was conceived by physics professor Richard Muller and his entrepreneurial daughter Elizabeth Muller who were both skeptical of the rise in global temperatures reported by the panels of climate scientists organized by the United Nations. As an independent non-profit organization, the Berkeley Earth group independently re-analyzed weather records for potential biases in data selection, data adjustment, poor station quality, and the urban heat island effect, caused by an increasing urban land surface. The results of the independent study confirmed the same conclusions experts at the United Nation panels had found. Many other scientific organizations have reanalyzed the available data, and all show a significant warming of the Earth’s atmosphere over the last century and half. Science is about re-testing, and the constant scientific re-evaluation of available data has continued to confirm the rise of global temperatures on Earth, but how hot will Earth’s atmosphere become with increasing amounts of carbon dioxide?
Climate sensitivity to increasing carbon dioxide is a major focus of ongoing research. Using historical data and climate models, climatologists have estimated a broad range of increasing global temperatures between 1.5°C to 4.5°C with a doubling of pre-industrial carbon dioxide to 560 ppm (in 2020 it is 410 ppm in Hawaii). Most studies suggest an increase of 3.1°C global increase by the year 2060. This would translate in winter temperatures in Salt Lake City for the coldest month of December having average highs of 44 degrees and lows of 36 degrees Fahrenheit, above freezing temperatures required for snow accumulations. The number of days above 100°F in the summer would increase dramatically for the city.
One of the challenges in estimating or predicting climate is understanding the time that it takes for changes in carbon dioxide to result in increasing global temperatures. For example, scientists define three ways to measure climate sensitivity. Equilibrium climate sensitivity (ECS) models suggest that there is a long time period between increases in carbon dioxide concentration and rising global temperatures, due to heat being absorbed by the Earth’s oceans. It takes into fact that heat absorption of the oceans will reach an equilibrium, and may result in a faster rate of temperature rise once this occurs. Transient climate response (TCR) models limit the growth of carbon dioxide to 1% each year (based on historical rise) and assumes the oceans will continue to serve as a sink for rising heat in the atmosphere and remain out of equilibrium with the atmosphere. The Earth system sensitivity (ESS) models attempt to include negative and positive feedbacks, such as the reduction of Earth’s albedo from melting sea ice and snow (causing more sunlight to be absorbed by the ocean and land surface), increases of wild fires (releasing more carbon dioxide), and changes in Earth’s vegetation, and the release of methane gasses from the Arctic. Changes in Earth’s cloud cover also plays a factor in these estimates, since clouds may increase with rising temperatures (causing temperatures to cool), although direct evidence of this is currently lacking from satellite data. Each model results in slight differences in the estimated rise in global temperatures, but most fall within a rise of 1.5 to 4.5°C, thus the Paris Agreement of 2016, with a goal of limiting the rise below 2°C is ambitious.
Projecting rising global temperatures forty years into the future may seem overly prescient, but there is a good chance that you, and your family will be living in this new warmer climate of the near future. These next forty years will ultimately determine the course for the next forty years that follow that. If allowed to increase, global temperatures will rise by 6°C by 2100, drastically limiting the number of days below freezing for higher elevations, with average warm temperatures in Salt Lake City in July above 100 degrees Fahrenheit. While it is difficult to imagine this abrupt change to the planet’s climate, one major concern for the future habitability of the planet is how these changes will affect the availability of water. In the next section you will learn about Earth’s water, from its oceans, seas, lakes, rivers, and ice, to the water that you drink every day.
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## References

* ↑ Saad & Jones (2016). "Gallup Poll".
* ↑ Reinhart (2018). "Gallup Poll".
* ↑ Milman (2015). "James Hansen, father of climate change awareness, calls Paris talks 'a fraud'". Guardian.