by Pielke et al., 2016 in PhysicsToday
To date, most reporting on climate has focused on the possibility of catastrophic warming due to carbon dioxide and other greenhouse gases released into the atmosphere. The assessment of climate change risk has essentially been distilled to a single metric: the global average surface temperature. That reality was evident at the 2015 United Nations Climate Change Conference in Paris, where the central negotiating point was whether the global temperature rise should be limited to 1.5 °C or 2 °C. Indeed, a 2016 opinion piece by Simon Lewis (University College London and the University of Leeds, UK) states that, “by endorsing a limit of 1.5 °C, the [Paris] climate negotiations have effectively defined what society considers dangerous.”
But the reality of humans’ impact on climate is exceedingly complex.2 Even if greenhouse gas emissions could be elimi- nated completely, other harmful anthropogenic sources of cli- mate change would remain. And even if global average tem- peratures were contained, human impacts on climate would manifest in other potentially dangerous ways.
One often overlooked human factor is land use. Deforestation, dry land farming, irrigated agriculture, overgrazing, and other alterations to the natural landscape can disrupt Earth’s natural balances and change weather patterns. As with the addition of CO2into the atmosphere, the effects can last for decades or longer and affect regions distant from the original offense. Given continued rapid population growth, they threaten to be irreversible.