The passage discusses the changes in decadal mean sea surface temperature (°C) and the impact of CO2 forcing on the ocean thermohaline circulation. It highlights the potential for monitoring systems based on repeated hydrographic sections and current-meter measurements to detect changes in thermohaline circulation due to increased greenhouse gas levels. The effectiveness of such monitoring systems depends on the natural variability in the circulation elements, which has not yet been fully quantified from observations. The text also references various studies and models that support these findings, including those on ocean-atmosphere interactions, climate change, and the influence of CO2 on sea surface temperatures.The passage discusses the changes in decadal mean sea surface temperature (°C) and the impact of CO2 forcing on the ocean thermohaline circulation. It highlights the potential for monitoring systems based on repeated hydrographic sections and current-meter measurements to detect changes in thermohaline circulation due to increased greenhouse gas levels. The effectiveness of such monitoring systems depends on the natural variability in the circulation elements, which has not yet been fully quantified from observations. The text also references various studies and models that support these findings, including those on ocean-atmosphere interactions, climate change, and the influence of CO2 on sea surface temperatures.