Global Change Research Centre AS CR, v.v.i.

 What is global climate change?
Global climate change is according to United Nations Framework Convention on Climate Change (UNFCCC) defined as ‘a change of climate which is attributed directly or indirectly to human activity that alters the composition of the global atmosphere and which is in addition to natural climate variability over comparable time periods’. So if we talk about global climate change, we are always talking about the changes caused by humans.

 What is climate?
Climate, in a broader sense, is a climatic state of the Earth system which can be statistically described. In a narrower sense, climate ‘is usually defined as the average weather, or more rigorously, as a statistical description in terms of mean value and variability of relevant quantities through the time periods ranging from months to thousands or millions of years. The classical period for averaging of variables is 30 years, as defined by the World Meteorological Organization’ (from the Glossary of AR4 Synthesis Report; some other explanations on this page are also paraphrased from that source).

 What is Earth climate system?
The climate system is the very complex and complicated system composed of five main components (atmosphere, hydrosphere, cryosphere, land surface and biosphere) and their mutual relationships.

 Is the Earth climate system constant?
No. The climate system is developing in time. This development has two reasons. First, the climate system is evolving through the influence of internal dynamics. Second, the climate system is evolving through the influence of external factors or forcing. Typical examples of external forcing are volcanic eruptions, changes in solar output and anthropogenic forcing (includes mainly changes in the atmosphere composition and land use change).

 What is the role of temperature in the Earth climate system?
Average global temperature is a basic, most simple, and at the same time very useful indicator of the state of the climate.

 What is global warming?
Global warming is a term for the increase of the near surface temperature (at a height of 2 m above the ground), averaged over the global surface.

 Is global warming really happening?
Yes. In the last 40 years, the global average air temperature increased by 0.6 °C. The temperature rise amounts to 0.2 K (kelvin, the same as degree Celsius) per decade already.

 Is the warming occurring everywhere in Earth?
No. Global warming is uneven. Warming is most significant in the Arctic and in winter.

 Why the term global warming is used when there is cooling in some places?
The reason is the global balance of the radiative fluxes. On average, the Earth emits less heat into space than it absorbs from the Sun. Therefore, it is heating up globally.

 What is the difference between heat gains and losses?
The difference is approximately 1 watt per square metre of the Earth surface.

 What was the thermal balance in the past?
The imbalance was close to zero during the past several thousands of years.

 What is causing the current thermal imbalance?
The increased (and further rising) concentration of greenhouse gases in the atmosphere.

 Why is the concentration of greenhouse gases increasing?
Concentration of greenhouse gases increases mainly as the result of fossil fuels combustion, but also due to deforestation, soil degradation and agriculture in general.

 What is happening with the excess heat?
The Earth keeps it. At least 90 % goes to the oceans, just a small percentage is manifested as increasing air temperature. This is the reason why the global air temperatures increased by ‘mere’ 0.8 °C during the last 100 years.

 Why it is not possible to ignore the temperature increase of 0.8 °C?
Because the temperature of the Earth is similar to that of a human body. An increase of 0.8 °C is a serious problem; increase of 5 °C might be lethal for humanity.

 Why the temperature increase is such a serious problem?

Because a small change in the average temperature causes big changes in the occurrence of various types of weather. For human, as well as natural systems which were developed during the considerably stable climate prevailing since the end of the last ice age, this has serious consequences.

What is at stake: water availability, agricultural productivity, forests and fisheries, occurrence of excessive heat or humidity, formation and spreading of poisonous air pollution, geographic distribution of diseases, damage from wind storms, floods, droughts and fires.

In the future, we might face also the loss of territories as a result of sea level rise, as well as increasing expenditures allowing for the functioning of our technical systems in previously unseen conditions. New ‘Migrations of Peoples’, even faster extinction of species and disappearance of whole ecosystems, and geochemical disruption of the oceans might be expected.

The existing inhabited regions, populated up to the limit of their capacity, are wholly dependent on the inherited climate patterns. The unleashed disruption of climate patterns becomes the driver of the global change.

 What does the term global change mean?
Global change is characterized as broad spectrum of biophysical and socio-economic changes, which change the functioning of the Earth as a system at the planetary level (changes in climate, ocean and land productivity, ocean an atmospheric chemistry, ecosystems). The result is the change in the ability of Earth to support life.

 Is there an evidence of global change?
Yes. Global change is not a matter of faith, but a matter of scientific understanding, therefore it can be proved in many ways – by Earth radiation imbalance, increase of carbon dioxide concentration, increase of ocean temperature, decrease in biodiversity etc. All of these parameters can be mathematically expressed.

 What is the main research topic of the CzechGlobe?
Observing of the climate parameters, analysis of the development of these characteristics, experiments aimed at understanding of the climate change impacts and proposals of the measures, which will enable human development under the conditions of global change.



Further information regarding the basics of global change (Kyoto protocol, El Niño etc.) can be found in the Glossary of AR4 Synthesis Report.