Our journey to net zero – part 1
In a landmark move in June 2019, the UK set a worldwide precedent as the first major economy to enact laws aiming to eliminate its contribution to global warming by 2050.
This decision was crucial and timely, given the irrefutable reality of the climate crisis. But some sceptics wonder how can we be so certain.
The evidence for global climate change is vast and comes from multiple, independent lines of investigation. One critical study looks at ice cores – long cylinders extracted from ice sheets in Greenland and Antarctica, and from glaciers worldwide. These cores provide a treasure trove of data, allowing scientists to examine climate conditions dating back 800,000 years.
Understanding ice cores
As snow layers accumulate over time, they compress into ice, encapsulating air bubbles, particulates and other substances. This process creates a chronological archive of Earth’s atmosphere, preserving data on temperatures, gas compositions (like CO2 and methane), volcanic activities, and even solar and sea-ice variations. Through these records, scientists have been able to recreate past climate conditions with extraordinary accuracy.
Ice cores not only offer a continuous view of climate changes, including temperature and precipitation shifts, but also the concentration of greenhouse gases, offering insights into their impact on global temperatures.
Key insights from ice cores
Ice cores provide precise dating of past events, linking climate shifts to specific timelines. Comparing data from before and after the Industrial Revolution reveals the significant human impact on the atmosphere and climate. Remarkably, CO2 levels and global temperatures have mirrored each other closely over the past 800,000 years. However, CO2 concentrations in the atmosphere surged by 47% after the Industrial Revolution – an unprecedented increase in recorded history.
Furthermore, direct CO2 measurements from the Mauna Loa Observatory and similar sites worldwide corroborate a consistent rise in CO2 levels since the industrial era, paralleling an increase in global temperatures.
Mounting evidence for climate change
- Recent decades have been the warmest since modern records began in the 19th century, with 19 of the warmest years occurring in the last 20, culminating in 2023 as the hottest year globally.
- Ocean temperature measurements, especially in deeper waters, indicate significant warming trends.
- Satellite and ground observations document the rapid melting of ice sheets in Greenland and Antarctica, contributing to rising sea levels.
- Glaciers are receding at unprecedented rates globally.
- There is an uptick in the frequency and intensity of extreme weather events, such as heatwaves, droughts, heavy rainfall and hurricanes.
- A shift in many plant and animal habitats towards higher altitudes and latitudes in response to changing temperatures and precipitation patterns, with a startling 69% decline in global biodiversity since 1970.
- Changes in seasonal phenomena, like flowering and migrations, align with temperature variations.
- The isotopic analysis of CO2 confirms the majority of the increase results from fossil fuel combustion, distinct in carbon isotope signature from other sources.
- A unanimous agreement among global scientific bodies acknowledges human-driven climate change.
- The Intergovernmental Panel on Climate Change (IPCC) reports a 95–100% probability that human activity is the dominant cause of the warming observed since the mid-20th century.
The evidence is clear: Earth’s climate is warming, predominantly due to human actions – and it’s imperative we respond.
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