Human Carbon Dioxide Emissions Reverse 2000 Years of Arctic Cooling

In summary, a recent study has shown that Arctic temperatures in the 1990s were the warmest they have been in at least 2,000 years, with a cooling trend due to Earth's orbital cycle being overcome by human-caused greenhouse gas emissions. This warming trend started much earlier than global warming and is amplified by various factors, including the albedo flip and the dryness of the Arctic atmosphere. While the long-term effects of CO2 are a concern, they are currently being overshadowed by short-term events such as El Nino and La Nina.
  • #1
Skyhunter
http://www.ucar.edu/news/releases/2009/arctic2k.jsp [Broken]

Arctic temperatures in the 1990s reached their warmest level of any decade in at least 2,000 years, new research indicates. The study, which incorporates geologic records and computer simulations, provides new evidence that the Arctic would be cooling if not for greenhouse gas emissions that are overpowering natural climate patterns.

The associated albedo flip will amplify the warming.
 
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  • #2
One of the arguments against AGW causing problems is that the spectra where CO2 absorbs IR is saturated by water absorbing. This is not a problem with the arctic atmosphere. Its too dry.

This is not the only source of Arctic amplificaiton but it is one of them.
 
  • #3
The new study is the first to quantify a pervasive cooling across the Arctic on a decade-by-decade basis that is related to an approximately 21,000-year cyclical wobble in Earth's tilt relative to the Sun. Over the last 7,000 years, the timing of Earth's closest pass by the Sun has shifted from September to January. This has gradually reduced the intensity of sunlight reaching the Arctic in summertime, when Earth is farther from the Sun.

The research team's temperature analysis shows that summer temperatures in the Arctic, in step with the reduced energy from the Sun, cooled at an average rate of about 0.2 degrees Celsius (about .36 degrees Fahrenheit) per thousand years. The temperatures eventually bottomed out during the "Little Ice Age," a period of widespread cooling that lasted roughly from the 16th to the mid-19th centuries.

Even though the orbital cycle that produced the cooling continued, it was overwhelmed in the 20th century by human-induced warming. The result was summer temperatures in the Arctic by the year 2000 that were about 1.4 degrees C (2.5 degrees F) higher than would have been expected from the continued cyclical cooling alone.

"If it hadn't been for the increase in human-produced greenhouse gases, summer temperatures in the Arctic should have cooled gradually over the last century," says Bette Otto-Bliesner, an NCAR scientist who participated in the study.

attachment.php?attachmentid=20509&stc=1&d=1252598357.jpg


So, while "Global Warming" did not offically start until about 1950, "Artic Warming" started far sooner.

Could we call it around 1900?
 

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  • #4
dorlomin said:
One of the arguments against AGW causing problems is that the spectra where CO2 absorbs IR is saturated by water absorbing. This is not a problem with the arctic atmosphere. Its too dry.

This is not the only source of Arctic amplificaiton but it is one of them.

CO2 does not have an instantaneous effect. The reason CO2 has an effect on climate is due to the fact that it is a long lived greenhouse gas.
 
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  • #5
Currently the ongoing increase of CO2 in the atmosphere is contributing about 0.015C/year to average annual global temperatures. This value is so small that it is hardly noticeable.

El Nino an La Nina on the other hand can swing global temperatures about 0.3C within a year or two. So, while CO2 additions do have a long term impact, it can be easily overwhelmed in the short term. It takes about 20 years of CO2 addition (at current rates) to approximately equal the amount of temperature swing we see from El Nino/La Nina (0.3/0.015).
 

1. What is the significance of the study on "Human Carbon Dioxide Emissions Reverse 2000 Years of Arctic Cooling"?

The study highlights the impact of human activities on global climate change and specifically focuses on the Arctic region. It suggests that human carbon dioxide emissions have reversed a natural cooling trend that has been present in the Arctic for the past 2000 years.

2. How was the study conducted?

The study was conducted by analyzing historical data from ice cores and tree rings, as well as modern data from atmospheric measurements. Researchers also used climate models to simulate the effects of human carbon dioxide emissions on Arctic temperatures.

3. What are the main findings of the study?

The study found that the Arctic has been experiencing a natural cooling trend for the past 2000 years, but human carbon dioxide emissions have caused a reversal in this trend. This has resulted in a rapid increase in Arctic temperatures, which has significant consequences for the region's ecosystems and global climate.

4. How do human carbon dioxide emissions affect Arctic temperatures?

Human carbon dioxide emissions contribute to the greenhouse effect, trapping heat in the Earth's atmosphere and causing global temperatures to rise. In the Arctic, this warming effect is amplified due to the region's sensitivity to climate change, resulting in accelerated melting of sea ice and permafrost.

5. What are the implications of this study?

This study highlights the urgent need to reduce carbon dioxide emissions and mitigate the effects of climate change. It also emphasizes the importance of understanding the long-term consequences of human activities on the environment and the need for more sustainable practices to protect the Arctic and the planet as a whole.

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