Climate Change

‘Climate’ refers to the ‘everyday’ weather trends, including the overall range of weather for that time of year or season. Today meteorologists carefully measure many aspects of the weather to build up a better picture of climate, such as temperature, humidity, precipitation and more. As daily conditions are measured, you can build a better picture of trends and anomalies overtime.

Climate Change or ‘Global Warming’ typically refers to the recent 200 year warming period experienced on the globe. Climatic changes have been occurring for millennia, causing major changes in temperate, hydrology and growth and decline of ice sheets. Climatic changes are a natural phenomenon, however, increased climate change and pressure is typically seen as the fault of humanity. By comparing historic climate change, such as in ice cores, tree rings and fossils, we can ascertain what is ‘normal’ climate change.

Weather data from 1999 show a mass disturbance in global climates, with records being broken, and continue to be broken. Extreme weather events are one indicator of climate change, such as flooding events from excess rainfall, to drought and heatwaves, as well as typhoons or cyclone events. According to the Centre for Research on the Epidemiology of Disasters (CRED), the world encountered 315 cases of natural disasters in 2018, mainly climate-related. This included 16 cases of drought, 26 cases of extreme temperature, 127 cases of flooding, 13 cases of landslides, 95 cases of storms and 10 cases of wildfire. The number of people affected by natural disasters in 2018 was 68.5 million, with floods, storms and droughts accounting for 94% of total affected people.

As a result of the accumulation of greenhouse gases emitted in the past, and the inertia of the climate system, the rate of global warming is projected to be substantially faster than in the last few decades, largely irrespective of the emission scenario (Meehl and Stocker 2007).

The Earth’s climate has never been stable and historical data shows this, however common concensus and data shows human activity has altered the global climate. Computer models are increasing in their accuracy at predicting weather events and climate change impacts.

Research climate change and its impact on different regions, such as cities and rural areas, as well as Western Europe, Africa and the Australasian continent to understand the difference of impacts. You can also research what people, organisations and governments are doing to combat climate change – if at all!

There are many factors that affect the global climate system:

The Atmosphere

The atmosphere is the most variable subsystem, which is sensitive to external influences. The composition of the air, such as Oxygen and Carbon Dioxide levels, is very important for climate. Carbon Dioxide allows short-wave radiation from the Sun to pass through, which is then absorbed by the Earth’s surface and re-radiated back to space as a long-wave (infra-red) radiation. Carbon Dioxide absorbs the long-wave radiation, causing temperatures to increase, as it traps radiation that would otherwise escape. The is referred to as the Greenhouse Effect. We need the Greenhouse Effect as it maintains temperatures on Earth, and it has ‘stabilised’ somewhat over millennia. Many years ago, carbon dioxide levels were much higher, and organisms evolved to adapt to this and absorb carbon dioxide – like plants – otherwise storing carbon and stabilising the atmosphere. The balance has been disrupted by increased greenhouse gases, like carbon dioxide, methane and water vapour. The release of carbon into the atmosphere through fossil fuel consumption, carbon that had been stored and is being re-released, has created the Enhanced Greenhouse Effect.

The Oceans

The surface layers of the ocean respond slowly to external influences, and it good be hundreds of years before the effects are felt in the deep ocean. The oceans play a role in carbon storage, namely storing dissolved Carbon Dioxide. Changes therefore to the oceans could affect their ability to retain carbon dioxide and impact the Atmosphere. Water has higher heat capacity than air, and oceans store a lot of energy. This accounts for the lessened seasonal differences in the Southern hemisphere, dominated by the oceans, unlike the Northern hemisphere dominated by the continents. Proximity to the ocean affects climate greatly. Oceans cover c. 71% of the Earths surface, though this has not always been the case due to continental change. As land masses move towards the poles, glaciation occurs and affects the global temperatures by increasing cooling, and likewise as they melt, increase heating. Orogenies, which is an event that results in structural ‘deformation’ and ‘compositional’ differentiation of the Earth’s lithosphere or crust, equally impact air flow and the Atmosphere.

The Land

Land changes, such as orogenies, as well as land-use changes have a significant impact on Climate Change. Volcanic eruptions can have short-term impacts by emitting ash, gas and dust into the air blocking the sun or blocking radiation.

Research some volcanic eruptions and compare against the global climate thereafter, you should see a marked decline in temperatures.

The Biosphere

The Biosphere concerns biological matter, flora and fauna. Vegetation affects many aspects, including:

  • The Albedo of the Earths Surface – namely how much it reflects radiation
  • Roughness of the surface – the roughness and how it affects wind speed
  • Evapotranspiration – the amount and rate which water leaves the ground
  • Atmospheric composition – Fauna typically removes carbon dioxide and replaces with oxygen. Dust in the air, typically a result of lack of vegetation, can block radiation and as desertification increases, it has the potential to block more radiation.

Humans are part of the biosphere and their activity has a significant impact on the climate system. Land use changes, deforestation for agriculture, have removed carbon sinks and increased carbon outlets. A change in atmospheric gases and desertification can be attributed to human activity.

The Cryosphere

The Cryosphere consists of the mountain glaciers and continental ice sheets, seasonal snow and ice cover on land, including sea ice. Ice and snow have a high albedo affect, high reflectivity, and currently 8% of the Earth is covered in permanent snow and ice. However, snow and ice cover fluctuates seasonally, though areas of glaciers and ice sheets change slowly.

Ampflied Warming
The greenhouse effect is a natural warming process. Carbon dioxide (CO2) and certain other gases are always present in the atmosphere. These gases create a warming effect. To Increase the amount of greenhouse gases intensifies the greenhouse effect. Higher concentrations of CO2 and other greenhouse gases trap more infrared energy in the atmosphere than occurs naturally. The additional heat further warms the atmosphere and Earth’s surface.

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