Our planet is vast. It is difficult to comprehend the scale. It is difficult too to comprehend the scale of humanity and the vast changes we’ve wrought in a lifetime.
Population, production and consumption have grown exponentially. Roads, railways, airlines, shipping routes. The digital revolution. We’ve created a globally interconnected society. Evidence is mounting we’ve entered the Anthropocene.Humanity is altering Earth’s life support system. Carbon dioxide emissions are accelerating. Greenhouse gas levels are unprecedented in human history. The climate system is changing rapidly.
The Intergovernmental Panel on Climate Change assesses the risks and options for societies. Its latest report states, it is extremely likely humans are the dominant cause of warming in the past 60 years. Without deep emissions cuts, it is likely Earth will cross the target of two degree Celsius above pre-industrial levels. The target set by international policy. This could happen as early as 2050. If emissions keep rising at current rates, a four-degree rise by 2100 is as likely as not. It is very likely heatwaves will come more often and last longer. The Arctic will warm faster than the global average. It is like sea ice will all vanish in summer within decades if high emissions continue. It is very likely sea-level rise will accelerate. Cities and coastal areas are vulnerable.
In general, wet regions are set to get wetter, dry regions drie out. Monsoons are likely to become longer, their footprint likely to grow and downfalls likely to intensify. The acidity of the ocean has increased 26% since the start of the industrial revolution. The full consequences of all these changes on the Earth system are unknown. Humanity’s carbon footprint is huge. Societies will need to adapt to climate change. The scale of change depends on decisions made now.
Can we remain below two degrees? It is possible. But it is up to societies now to decide the future we want. For a likely chance of achieving the two-degree target, societies can emit another 250 billion tonnes of carbon. We burn about 10 billion tonnes of carbon a year. At current rates we will use this budget in about 25 years.