By the end of 2021, we had one of our most successful years ever with return on capital employed approaching 10%, our highest since 2014; the successful integration of Noble Energy, while more than doubling initial synergy estimates; and record free cash flow, 25% greater than our previous high.
2021 was also the year when Chevron accelerated our efforts to advance a lower carbon future by forming Chevron New Energies, an organization that aims to grow businesses in hydrogen, carbon capture and offsets; introducing a 2050 net zero aspiration for upstream scope one and two emissions and establishing a portfolio carbon intensity target that includes scope three emissions and more than tripling our planned lower carbon investments.
Our record free cash flow enabled us to strongly address all four of our financial priorities in 2021: a higher dividend for the 34th consecutive year; a disciplined capital program, well below budget; significant debt paydown with a year-end net debt ratio comfortably below 20% and another year of share buybacks, our 14th out of the past 18 years.
The Noble acquisition and increasing capital efficiency enabled us to maintain a five-year reserve replacement ratio above 100%.
We reported fourth quarter earnings of $5.1 billion or $2.63 per share.
Adjusted earnings were $4.9 billion or $2.56 per share.
The quarter's results included three special items: asset sale gains of $520 million, primarily on sales of mature conventional assets in the U.S.; losses on the early retirement of debt of $260 million, which will result in significant future interest cost savings and pension settlement costs of $82 million.
Full year earnings were over $15 billion, the highest since 2014.
Compared with 3Q, adjusted 4Q earnings were down $770 million.
Adjusted earnings increased over $15 billion compared to the prior year, primarily due to increased realizations in upstream as well as improved refining and chemicals margins.
2022 production is expected to be flat to down 3% due to expiration of contracts in Indonesia and Thailand.
Excluding contract expirations and 2022 asset sales, we expect a 2% to 5% increase in production led by the Permian and lower turnaround activity in TCO and Australia.
We reaffirm our prior long-term guidance of a 3% production CAGR through 2025, and we'll share more about our long-term outlook at our upcoming Investor Day.
Affiliate dividends are expected to be between $2 billion and $3 billion, depending primarily on commodity prices and margins.

Summary:
We reported fourth quarter earnings of $5.1 billion or $2.63 per share.
Adjusted earnings were $4.9 billion or $2.56 per share.