Two usages of ‘climate sensitivity’ co-exist: one climatological and one ecological. The earlier climatological usage quantifies the sensitivity of global mean surface temperature to atmospheric CO₂, with formal variants differing by timescale and processes. The ecological usage, renamed here as ecoclimate sensitivity, is defined as a change in an ecological response variable per unit climate change. The two concepts are treated very differently: climatologists have focused on reducing uncertainty of global climate sensitivity estimates, while ecologists have focused on the multivariate processes governing variations in ecoclimate sensitivity across drivers, response variables, and scales. Because radiative forcing scales logarithmically to [CO₂]_atm, ecological impacts per ppm [CO₂]_atm often also scale logarithmically, although non-linear ecoclimate sensitivities can alter this expectation. Critically, past estimates of climate and ecoclimate sensitivity carry an implicit tradeoff, in which smaller estimates of climate sensitivity indicate higher ecoclimate sensitivities. For the LGM, estimates of equilibrium climate sensitivity have narrowed to 2.4 to 4.5 °C, while high ecoclimate sensitivity is indicated by post-glacial biome conversions, continental-scale species range shifts, and high community turnover. We introduce a new term, ecocarbon sensitivity, defined as the product of global climate sensitivity, local ecoclimate sensitivity, and a global-to-local climate scaling factor. Given past biospheric transformations, we can expect high sensitivity of the terrestrial biosphere to current rises in [CO₂]_atm, a conclusion that is insensitive to estimates of climate sensitivity. The next frontier is better quantification of the processes governing the form and variations of ecoclimate and ecocarbon sensitivity across systems and scales.

“气候敏感性”有两种用法并存：一种是气候学的，一种是生态学的。早期的气候学用法量化了全球平均表面温度对大气CO ₂的敏感性，其形式变量因时间尺度和过程而异。生态利用在这里更名为生态气候敏感性，被定义为每单位气候变化的生态响应变量的变化。这两个概念的处理方式截然不同：气候学家专注于减少全球气候敏感性估计的不确定性，而生态学家则专注于控制驱动因素、响应变量和尺度之间生态气候敏感性变化的多元过程。由于辐射强迫与 [CO ₂ ] _atm呈对数关系，因此每 ppm [CO ₂ ] _{atm 的}生态影响通常也呈对数关系，尽管非线性生态气候敏感性可能会改变这一预期。至关重要的是，过去对气候和生态气候敏感性的估计存在隐含的权衡，其中气候敏感性的较小估计表明生态气候敏感性较高。对于末次盛冰期，平衡气候敏感性的估计已缩小至 2.4 至 4.5 °C，而高生态气候敏感性则表现为冰期后生物群落的转变、大陆规模的物种范围变化和高群落更替。我们引入了一个新术语，生态碳敏感性，定义为全球气候敏感性、当地生态气候敏感性和全球到当地气候比例因子的乘积。鉴于过去的生物圈转变，我们可以预期陆地生物圈对当前 [CO ₂ ] _atm的上升高度敏感，这一结论对气候敏感性的估计不敏感。下一个前沿是更好地量化跨系统和规模的生态气候和生态碳敏感性的形式和变化的过程。