What is climate?

Climate is the average weather, the weather over a long period of time, or put simply, the weather in concentrate. To understand the climate one needs to observe the weather over long periods of time so that single extreme weather situations do not have an undue effect on the averages.

How do we measure the climate?

There are many ways in which to observe climate and climate changes. The most common observations are simply temperature and precipitation measurements. Other aspects of the climate are humidity, wind strength and direction, atmospheric pressure, cloud cover and sunlight intensity. In Arctic regions information about the climate can also be gathered from the persistence of ice and snow cover. Long-term, continuous environmental monitoring is therefore essential.

The Norwegian Polar Institute is conducting research on past climates as well as today’s physical processes involving the ocean, sea ice and terrestrial ice. In Antarctica our researchers have contributed to the collection of climate information by drilling ice cores in the thick inland ice of Dronning Maud Land. Trapping atmospheric gases in air bubbles, the ice is a climate archive that provides information reaching 900 000 years back in time. Deep water formation and sea ice is being investigated in Fram Strait, as is the size and mass balance of Svalbard's glaciers. For more information, see "Polar climate".

Is the climate changing?

The climate is constantly undergoing natural change, but most researchers today agree that human-made alterations of the atmosphere have contributed to, and will continue to affect, changes in the global climate system. In its third assessment of the state of the climate, UN’s Intergovernmental Panel on Climate Change (IPCC) pointed to several models that will lead to a 40% higher heating of the Arctic during the winter than the global average. The fourth assessment is being released in the spring of 2007.

What factors influence the climate?

The influx of energy from the sun is the main basis for the Earth’s weather. This energy is distributed unequally over the globe through geographical differences in sunlight intensity and variation in winds and ocean currents. The Earth’s climate is dramatically influenced by the greenhouse effect. The greenhouse effect is a natural condition of warming of the atmosphere: heat escaping from the surface of the Earth is reflected back to the Earth by clouds and gases in the atmosphere. Without the greenhouse effect, the Earth would be covered by a large ice cap. Human-made climatic changes are most likely caused by human effects on the greenhouse effect through the release of climate gases such as carbon dioxide (CO₂), methane (CH₄) and fluoride gases.

How is the Arctic environment influenced by climate changes?

Arctic systems have features that makes them special in comparison to other ocean areas, and these features are decisive in how these systems are influenced by climate changes:

• Large seasonal changes, in particular in incoming sunlight.
• Ice cover, both permanent and seasonal.
• Large influx of freshwater from rivers and ice melt.
• High reflection of sunlight because of snow and ice covers. 
• Little precipitation.

The reason for the faster warming of the Arctic is found in complex feedback mechanisms between the atmosphere, ocean and ice. White snow and ice reflect most the energy from the sun while dark oceans and land absorbs this energy. As snow and ice cover diminishes, more and more energy is absorbed and the warming becomes self-reinforced through this positive feedback mechanism. It is therefore hard to predict how fast the changes will occur. The processes have been advancing at a faster pace than most researchers have predicted.

We know that the warming of the Arctic is considerably more pronounced than the rest of the globe. Despite this, climate change models are riddled with greater uncertainties the further north one moves. This is mostly due to the limited geographical area covered by the research, and because of the self-reinforced warming effect.

The Nor-ACIA secretariat, which is a Norwegian continuation of the Arctic Climate Impact Assessment (ACIA), has its offices within the Norwegian Polar Institute. The ACIA report can be found at ACIA's website.

The big picture

Even though we need more knowlege about large areas of the Arctic, we can still claim with certainty that the average global surface temperature is increasing. The really big question we need to answer is if this increase is part of a natural cycle or if it is the result of humankind's release of climate gases into the atmosphere.

At the moment this question can only be answered by global climate models. All climate models predict a continued and accelerated warming. Additionally, most models indicate that the warming will be higher in the Arctic compared to other areas.

Global climate models are not perfect. Researchers that work with these models are aware of the models' shortcomings and understand where to focus their efforts in order to sharpen their models' predictive powers. Despite their shortcomings these models are the best tools we have at the moment. The models should be taken seriously because many of the consequences we are facing, such as ecosystem changes and sea level rise from warming oceans and melting glaciers, are potentially irreversible effects.