Scientific investigation has revealed an error in ocean temperature measurements dating back decades, indicating that the world's seas are warming and rising at a faster rate than previously thought. A team of international scientists identified the error in data collected from a common probe called an XBT, and after correcting it and conducting a thorough statistical analysis, they determined that ocean warming and sea level rise have been underestimated. The team's findings, published in the journal Nature, show that the rate of ocean warming between 1961 and 2003 is actually 50 percent higher than previously reported. John Church, one of the authors of the report, had been skeptical of the historical data due to inconsistencies with computer model results of climate and ocean trends. Church, a senior research scientist at the climate centre, stated that after realigning the observations, the models now align much better with the observations than before. By statistically comparing XBT observations with research ship observations, one can estimate the errors associated with XBTs. This is important because the oceans hold over 90 percent of the heat in the planet's climate system and can mitigate the effects of climate change. Warmer water expands, causing sea levels to rise, along with run-off from melting glaciers and ice sheets. Church's team estimated a global average surface warming of 0.4 degrees Celsius between 1961 and 2003, with sea levels rising 1.6 millimeters per year during this period, as per Church. Church mentioned that sea levels have been rising at a rate of over 3 mm per year since 1993 due to increased fossil fuel consumption. XBTs were previously used by commercial vessels to measure ocean temperatures, but they have now been largely replaced by satellites and permanent probes. XBTs were disposable instruments that were thrown overboard with a wire attached to measure temperatures as they sank. Church explained that inaccuracies in measuring the depth of the instrument could lead to errors in temperature readings. To address this issue, Susan Wijffels and her colleagues developed a mathematical formula to correct these errors. Combining a broader statistical analysis of global ocean temperature data with other factors revealed a more accurate representation that aligned with widely used computer models predicting climate and ocean behavior due to global warming. This new perspective shows a consistent rate of warming and an upward trend in that warming, which increases confidence in the reliability of future projections. Additionally, observations suggest that actual sea level rise is tracking towards the higher end of projected estimates, with the U.N. Climate Panel warning of potential sea level rise of up to 80 cm by 2100 if carbon dioxide levels are not controlled.