It will become hotter
How hot will it get?
IPCC climate projections operate with four different future scenarios, depending on the quantity of emissions we can cut. The climate projections are based on calculations with the climate models. These are based on the laws of physics and describe how temperatures, winds, humidity and clouds behave across the entire globe. In the figure below the historical emissions of greenhouse gases is shown in black. If we continue to emit the amount of greenhouse gases as we have done up until now, we will have a possible temperature increase of 5 degrees globally, which will have very serious consequences. If we emit less CO2,, the global warming will also be less.
Global temperatures have risen by about one degree since measurements began. 2014, 2015 and 2016 were record hot years, due to both the Pacific phenomenon El Niño (a natural phenomenon) and the underlying trend of global warming.
It is normal that the temperature varies from year to year due to natural variations in ocean currents, El Niño, volcanic eruptions, changes in the sun and the earth's orbit around the sun. But if we only had natural variability, the temperature would vary up and down, without rising over time.
Natural climate variations teach us that climate is sensitive to different conditions. Amongst other things, changes in known conditions will have an impact, such as increased concentrations of greenhouse gases. We know of no physical reasons to suggest that a change in the amount of CO2 would not have an effect. On the other hand, we see that the greenhouse effect is very strong on Venus, which has a thicker atmosphere of mainly CO2. The increasing trend after 1950 can only be accounted for by anthropogenic climate change - we see no corresponding long-term trend in for example sun changes.
CO2 and temperature
There is a correlation between CO2 and temperature that can be seen in data that goes back 800,000 years in time. In warm periods, the CO2 concentration will also increase due to the algae in the ocean and vegetation on land not being able to take up as much CO 2. When there is a lot of CO2 in the air it will, due to the greenhouse effect, become even warmer - until changes in the orbit around the sun force the temperatures down again. These natural changes occur over a very long time.
What is special now, is that in a very short space of time a very large amount of CO2 has been released into the atmosphere. During the pre-industrial period the CO2 concentration was below 300 ppm, while today it is 400 ppm. We consequently now have the highest value for at least 800,000 years. When the CO2 values continue to rise, the temperatures will also rise.
We understand the physical connection, which is that CO2 captures heat and slows the Earth's heat loss to space. This property of CO2 can also be measured in a laboratory. The video below shows how the temperatures and CO2 concentrations have varied together and are expected to follow each other in the years ahead.
It will become hotter in Norway as well
Norway is also becoming steadily warmer. Observations from monitoring stations throughout the country show that the average temperature has increased by one degree since 1900, and in the last 15 years alone the temperature has risen by half a degree.
If we compare this with today, we expect that the temperature towards the end of the century could increase by about 4.5 degrees if emissions continue as they are now. If we emit less, the temperature will also rise less, but even if we cut all emissions now, the temperature will continue to rise somewhat.
At present we are increasingly seeing new temperature and precipitation records being set, and it is not unrealistic that we could get up to 40 degrees in a couple of places in the summer of 2050, says meteorologist Bente Wahl in the video below.
Dangerous heat waves
During the heat wave in central Europe in the summer of 2003, 72,000 people died. Temperatures of over 40 degrees were recorded in France and 47 degrees in Spain. In the summer of 2010 there was a similar heat wave in Russia, where nearly 56,000 people died. We must expect more such heat waves in the future.
In some places of the world, such as North Africa and the Middle East, it may become so hot that it becomes uninhabitable. Here, the average temperature in the summer months will be above 35 degrees in 2100. When the average over three months is so high, the night temperatures are also very high, and there will be quite extreme temperatures during the middle of day. This will especially be a challenge for the major million cities that already create an urban heat island effect. Already within a few decades, it may be impossible to live in these areas. Currently they are home to hundreds of millions of people, who will become climate refugees.
In Europe, Turkey and Greece will get the hottest. The summer temperatures in Norway are calculated to be not as high, but for shorter periods it may get uncomfortably warm in parts of Norway. In addition to the direct effect of the heat, the increased temperatures will also cause more pollen and asthma problems in Norway.
Global warming will result in a higher sea level. This is both because warmer water expands and needs more space, and because ice on land melts and increases the amount of water in the oceans. Many million cities and densely populated areas are prone to flooding, and the world will experience displaced people to a much larger degree in the future. Many will flee because of sea level, but also from areas where it becomes too hot or dry to live.
Longer growing season
Climate change also creates some opportunities. In Norway, the temperature increases give better conditions for food production because the growing season becomes longer. Towards the end of the century, the growing season will increase by one to three months depending on the scenario and place.
But this does not only bring advantages. In southern Norway, the increased temperature may lead to an increased risk of summer drought and risk of forest fires. And when precipitation comes, it comes in much larger quantities than before. This can lead to flooded farmland.
An increased growing season can also give us new parasites and insects. Fungus attacks and plant diseases can change quickly in a changing climate. The prevalence of ticks are, for example, is expected to grow extensively in the southern parts of the country.
How big are the changes?
How big the changes will be is critically dependent upon how big the greenhouse gas emissions will be. Fewer emissions means less climate change, fewer negative consequences and less need for adaptation.
Examples of climate adaptation are physical installations that prevent landslides, surface water drainage, spatial planning, and barriers against the sea level. Indirect climate adaptation may include the development of new plant varieties that can withstand a new climate, planning, insurance schemes, economic governance, the protection of ecosystems, legislation and international agreements.
How will we manage an increased flow of people being displaced from places that are no longer habitable? One of the most important measures for climate adaptation are so-called 'early warning systems' that include accurate weather forecasts. An open data policy and access to reliable information is essential for safeguarding life and property in the future.