The conversation covers mechanisms connecting fossil fuel consumption to observable changes, including the ice albedo feedback loop where melting ice exposes darker surfaces that absorb more heat, ocean acidification, and the relationship between warmer oceans and more intense storms. Dr. Trenberth explains how a strong El Nino in the Pacific will likely bring heavy rains to drought-stricken California, potentially causing flooding after years of devastating wildfires.
Art presses Dr. Trenberth on solutions, and the scientist advocates putting a price on carbon to incentivize renewable energy innovation. Callers challenge the economic implications, while Dr. Trenberth notes that climate disasters already cost tens of billions annually and that sea level projections of two to three feet by 2100 could devastate coastal cities worldwide.
Key Moments
Climate change: not opinion, evidence: Trenberth invokes Moynihan's line about facts vs. opinions and lays out the convergent evidence: rising global temperatures, Arctic sea ice loss, warming oceans, sea level rise, and melting glaciers, concluding humans are the primary cause.
Tipping points and the melting of Greenland: Art presses on whether there is a point of no return. Trenberth says we likely cannot stop climate change, only slow and adapt. He warns of long-term tipping points like a full Greenland melt, which could ultimately raise sea levels by 7 meters (over 20 feet).
Ice-albedo feedback amplifies warming: Trenberth explains the ice-albedo feedback: as bright snow and ice melt, the darker surface beneath absorbs more solar radiation, accelerating further warming. He describes the same effect in mountain regions and Alaska.
Crossing 400 ppm CO2: Trenberth confirms 2015 will be the first year atmospheric CO2 exceeds 400 parts per million, up from a pre-industrial level of 280 ppm, a 40 percent increase he calls very well established.
Shooting the messenger and ruling out the Sun: Trenberth describes the political and oil-industry attacks on climate scientists as 'shoot the messenger,' addresses 'denier' framing, and explains that since 1979 satellite measurements show the Sun's variation is far too small to drive recent warming.