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Abstract Cosmic rays and solar energetic particles pose significant risks to satellites, space stations, and human space exploration. They also produce atmospheric radiocarbon (¹⁴C), which enters the carbon cycle and is recorded by paleoenvironmental proxies. Miyake events, rapid increases in atmospheric¹⁴C, first identified in annual tree rings and later confirmed through ice core¹⁰Be and³⁶Cl isotopes, are thought to result from extreme solar activity, are seven events identified over the last 14,300 years. However, uncertainty in annual¹⁴C measurements limits precise inferences about their timing and magnitude. This study examines uncertainties in¹⁴C during two Miyake events (774 CE and 993 CE) across trees with differing uptake, storage, and allocation of carbon. We hypothesize that tree species physiology affects tree‐ring Δ¹⁴C, with deciduous species recording lagged, attenuated tree‐ring Δ¹⁴C relative to evergreen species. Using Δ¹⁴C data from pine and larch in Mongolia and a larger multi‐species Northern Hemisphere data set, we employed a Bayesian framework to estimate the timing, duration, and magnitude of these two events. Our AMS results showed no differences in Δ¹⁴C between evergreen and deciduous species growing at similar sites during the 774 CE event. The 993 CE event was variable, but parameter estimates were consistent between species. Northern Hemisphere comparisons indicated that annual series of Δ¹⁴C from evergreen and deciduous conifers yielded relatively more precise modeled estimates of start date and duration relative to deciduous broadleaf species. Future studies should consider the role of species‐specific carbon allocation strategies and storage dynamics in determining the radiocarbon response to Miyake events. 

Abstract Warming in Central Asia has been accelerating over the past three decades and is expected to intensify through the end of this century. Here, we develop a summer temperature reconstruction for western Mongolia spanning eight centuries (1269–2004 C.E.) using delta blue intensity measurements from annual rings of Siberian larch. A significant cooling response is observed in the year following major volcanic events and up to five years post‐eruption. Observed summer temperatures since the 1990s are the warmest over the past eight centuries, an observation that is also well captured in Coupled Model Intercomparison Project (CMIP5) climate model simulations. Projections for summer temperature relative to observations suggest further warming of between ∼3°C and 6°C by the end of the century (2075–2099 cf. 1950–2004) under the representative concentration pathways 4.5 and 8.5 (RCP4.5 and RCP8.5) emission scenarios. We conclude that projected future warming lies beyond the range of natural climate variability for the past millennium as estimated by our reconstruction.