Climate Models:

• A prediction is a statement of probability that says something will happen tomorrow based on what we know today. Predictions tend to assume that changes in future conditions will not have a significant effect on the predicted outcomes
• A projection on the other hand is a statement of probability that says something could happen in the future if certain conditions develop
• The climate system is a very complex system that involves the atmosphere, oceans, ice, land, all living things on Earth.
• forcings: The climate can also be changed by events that are not part of the natural climate system, such as volcanic eruptions or increased CO₂ emissions from human activities
• Climate models are mathematical representations of the climate system
• Climate scientists then take lots of different data sources, equations and approximations and are able to put them together to create a climate model. They can then change one thing - like the amount of greenhouse gases in the atmosphere - and see how everything else changes
• how do we know what aspects of our climate system (temperatures, sea levels, CO₂ concentrations) were like before then?
  • Looking at the size of rings in tree trunks
  • Analysing the bubbles of ancient air and thickness of layers of snow in ice cores from glaciers and ice sheets.
  • Finding fossils and minerals deep under the seabed
• there are challenges to creating accurate projections of past climates. The data is limited (scientists weren’t using thermometers to measure air temperatures millions of years ago!), which makes it difficult to make precise estimates, and some parts of the climate system, such as rainfall and solar energy, are incredibly complex and can be challenging to simulate accurately
• By using several different well-considered scenarios of human responses to climate change (from doing nothing to rapidly reducing emissions), climate modellers can give policymakers an idea of the range of possible changes in climate resulting from different policy actions

Global Warming:

• When was the last time Earth was this warm? 5 million years ago
• By 2100, Earth’s average temperature is projected to increase by roughly 3.2°C above the pre-industrial levels
• Over the past 1 million years, Earth has experienced a natural cycle of ice ages and warmer periods. hese are not driven by humans but by slow changes in the planet's orbit that affect how it receives energy from the Sun. This gradual temperature change, averaging around 0.5°C over the past 10 thousand years, provided a stable environment supporting human civilisation's development.
• Until recently, the Earth was in a natural cooling phase, which started around 5 thousand years ago We were actually heading towards a new ice age, due in about 1.5 thousand years. However, after around 1850, global temperatures started to rise dramatically
• What do you think are the major factors that will affect temperature change over the next century?
  • how much GHGs are released
  • how the climate system reacts
  • changes in the tilt of the earth and shape of its orbit
• The sea is cooler than the land mainly because a larger proportion of the Sun’s heat energy is used to evaporate water rather than being absorbed to increase the sea surface temperature
• This evaporation not only means that the sea warms less than the land but it also causes more heat to flow from the oceans to the land than from land to oceans, so the difference in temperature increases even further
• Evidence suggests 80-90% of warming on land is caused indirectly by heat moving from warming oceans
• Therefore, many land areas are experiencing greater warming than the global average. For example, when global warming above pre-industrial levels has an average value of 1.5°C across the Earth, the average value across some land regions could be 3°C