Climate change over time

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Earth's climate has undergone dramatic transformations over the past 800,000 years, shaped by orbital changes, solar variability, volcanic activity, greenhouse gases, and catastrophic events. Examining this period provides valuable insights into the complexity and interconnectedness of Earth's systems.

The 800,000 year period is where we have evidence of past climate and atmospheric gas levels from ice cores sampled in Antarctica.

Climate Eras over the Past 800,000 Years
  • Mid-Pleistocene Transition (800,000-127,000 years ago): Transition from 41,000-year to 100,000-year glacial cycles, marked by the intensification of glaciations.

  • Penultimate Glacial Period (190,000-130,000 years ago): Vast ice sheets covered the Northern Hemisphere.

  • Last Interglacial Period (130,000-116,000 years ago): Warm conditions, with sea levels higher than today, also known as the Eemian.

  • Last Glacial Period (116,000-11,700 years ago): Earth entered another Ice Age with large-scale glaciation.

  • Holocene (11,700 years ago-present): Relatively stable climate, though fluctuations have occurred.

Subdivisions of the Holocene:

  • Early Holocene (11,700-6,000 years ago): Climate warmed rapidly, though fluctuations occurred.

  • Mid-Holocene (6,000-2,500 years ago): Relatively stable climate with slight cooling.

  • Late Holocene (2,500 years ago-present): Cooling and warming trends leading up to the present day.

Two small fluctuations during the Late Holocene are also of note.

  • Medieval Warm Period (900-1300 AD): A time of relatively warm conditions in the North Atlantic region.

  • Little Ice Age (1300-1850 AD): A period of cooler temperatures, with significant glacier advances in many regions.

Drivers of Climate Change

Climate change is influenced by various factors:

Orbital changes

Variations in Earth's orbit and tilt affect the amount of solar radiation received.

1992 Familt Portrait PIA00134 NASA/JPL

Solar variability

Changes in solar activity can influence Earth's climate.

Sun c NASA NASA

Volcanic activity

Volcanic eruptions release aerosols into the atmosphere, altering temperature and precipitation patterns.

Volcano c Pixabay Pixabay

Greenhouse gases

Changes in atmospheric composition, especially greenhouse gases, drive long-term climate shifts.

Atmosphere c NASA NASA

Asteroid impacts

Rare but significant events that release debris into the atmosphere, blocking sunlight and triggering secondary environmental changes.

Meteorite credit pixabay Pixabay
Recent Climate Change

Over the past 250+ years (from the start of the Industrial Revolution), human activities have altered Earth's climate:

Burning fossil fuels

Burning fossil fuels led to increased atmospheric carbon dioxide concentrations. Human-induced greenhouse gas emissions have caused global temperatures to rise at an unprecedented rate.

Fiddlers Ferry power station UK c Flickr Ian Carroll CC BY 2 0 Flickr / Ian Carroll CC BY 2.0

Land use changes

Deforestation and urbanisation have contributed to rising carbon dioxied levels.

Clear cut forest Oregon c Calibas CC BY SA 3 0 Calibas CC BY-SA 3.0
The current situation

According to recent studies, the average global temperature has increased by around 1.1° Celsius (1.9° Fahrenheit) since 1880. However, since 1975, the rate of warming has been even faster, with temperatures rising by about 0.15 to 0.20°C per decade.

Furthermore, data from Berkeley Earth indicates that the average temperature of Earth's land has risen by 1.5 °C over the past 250 years. According to research from the University of Arizona, this warming trend is unprecedented in the last 24,000 years.

The most recent data shows that 2023 was the warmest year on record, tying with several other years as the fifth warmest year since global records began in 1850. These changes are not absolute temperatures but anomalies compared to a baseline period from 1951 to 1980.

The rapid increase in global temperatures over the past few decades highlights the significant impact that human activities have had on the Earth's climate.