Reconstruction of temperature in the Northern Hemisphere over the past 2000 years.
Group of scientists from Syracuse University, New York, has been studied time period relating to the Middle Ages, it is very similar to the current "global warming."
He proceeded 500-1000 years ago, not only in Europe, according to researchers, but also in other continents way to the Antarctic, and was replaced by a "mini ice age". The most important thing in the opening can be considered that the medieval warming occurred without carbon dioxide, which is a major cause of global climate change.
However, other researchers (M. Mann and F.Dzhons) point out that the ancient warming was a local anomaly, and can not claim to global status and compared with current realities. Temperature over the last 2000 years has been more or less stable, but it became much growing after industrialization, when increased levels of harmful emissions into the atmosphere. It also stresses the low degree of reliability of the data of medieval temperatures.
The iceberg breaks off a huge chunk of ice.
The representative of the Syracuse University professor Lu insists, citing the results of the study sample ikaita rare mineral that lies in the cold waters of the Antarctic. According to Lu, the mineral is icy analogue limestone on which you can study quite accurately the temperature characteristics of the ancient world. Layers that contain many of the isotope oxygen-16, correspond to periods of warming, heavy isotope-18 — periods of cooling. When comparing the data samples ikaita and information about other sources of temperature between the established time line.
Harmful industrial emissions. Thorold, Ontario, Canada.
It is fair to note that the large deposits ikaita known only in northern Europe, but not worldwide. Despite this, Lu and his colleagues argue that what happened in Europe without warming carbon dioxide could have implications for global temperature rise, especially in Antarctica. This challenges the current theory, is accused of worsening climate, industrial air pollution.
Gases that cause climate change. Hamilton, Ontario, Canada.
Still, most of the modern scientific world is inclined to believe that in the Middle Ages was only warming coincidence, while now the cause of global change is obvious — it is the era of industrialization and as a result, air pollution, environmentally unsafe chemicals. At this point in the Earth's atmosphere contains 0,04% CO2 and its level a couple of decades can grow up to 0.07%. And you can not say with confidence that, as a thousand years ago, the warming will change the mini-cooling.
In general, alternative theories, like Professor Lu expressed, once again proving that you can not stop the research on such an important issue for the planet. It is important to continue to search for new evidence on the causes of global warming, and methods for prevention and control.